Zevachim 79a - More on Ta'am K'ikar

The gemara seems to conclude that by min b'sheino mino we follow ta'am, meaning that so long as the issur taste is realized in the heter, the food is assur. Tosafos discusses whether this concept is d'oraysa. The fact that Rava doesn't pick a number such as 60x or 100x, rather makes it dependent on the taste, leads Tosafos to say that the issue of ta'am k'ikar is d'oraysa. Tosafos rejects the opinion of Rashi in Chulin 98b who holds that we pasken ta'am k'ikar is only d'rabonon. In the long discussion, Tosafos also cites the opinion of R. Yosef D'orleans who says that although ta'am k'ikar is d'oraysa, it is only an issur aseh, a violation of a positive mitzvah for which there is no malkus. Rabbeinu Tam rejects this and holds that there would be malkus. The fundamental point in their argument is whether we consider ta'am k'ikar to be a new prohibition (Rabbeinu Yosef) or merely a giluy that this also qualifies as eating the item which is assur.

R. Akiva Eiger 78a asks why the gemara concludes from Reish Lakish that ta'am k'ikar is not d'oraysa from the fact that there is no malkus when the pigul, no'sar and ta'mei are mevatel each other. According to Rabbeinu Yosef that ta'am k'ikar is d'oraysa but there is no malkus since it is merely an a'seh, we could simply say here too that ta'am k'ikar is d'oraysa but there is no malkus? This is a very strong question on Rabbeinu Yosef because the gemara does seem to imply that we can't separate ta'am k'ikar being d'oraysa from the malkus. It is also intriguing that R. Akiva Eiger asks this question from Rabbeinu Yosef in Tosafos Chulin 99, rather than asking it from Tosafos on the very next page of Zevachim!

To me it seems that there is a very strong diyuk in Rashi that would answer both R. akiva eiger's question and Tosafos question. Tosafos (d.h. ma'siv) asks why do we challenge the gemara's proof from reish lakish that ta'am k'ikar isn't d'oraysa from the mishna that one can fulfill their mitzvah of matzah by eating a kezayis of matzah made from mostly rice flour (and a little wheat flour that gives ta'am in it). Why didn't the gemara ask from the myriad of places where we have a concept of ta'am k'ikar?

A careful reading of Rashi indicates that the gemara never meant to prove from Reish Lakish that ta'am k'ikar is not d'oraysa. It could be that Reish Lakish would submit that ta'am k'ikar is d'oraysa. The gemara was simply saying that we don't regard the ta'am to be as substantial as the ikar so that by merely eating a kezayis of something that has taste of issur he would get malkus. Rashi writes:

ושמע מינה נותן טעם ברוב לאו דאורייתא- הא דאמור רבנן בכל דוכתי איסור הנותן טעם בהיתר אוסרו ואף על פי שההיתר ברוב, לאו דאורייתא הוא ללקות עליו

Rashi clearly focuses on the malkus. Meaning, that it could very well be d'oraysa but there is no malkus since eating a kezayis of taste of issur isn't tantamount to eating a kezayis of actual issur. Based on this approach, Tosafos question is answered. The only clear case we can ask from is the mishna in chalah that allows one to fulfill matzah by eating a kezayis that only has a taste of wheat flour and not an actual kezayis of wheat flour. This indicates that ta'am k'ikar affects even the shiur, and doesn't just make the item assur. Based on this, R. Akiva Eiger's question is also answered. The gemara wasn't simply trying to say that ta'am k'ikar isn't d'oraysa. The gemara understands that even according to Reish Lakish, ta'am k'ikar may be d'oraysa. The gemara is only trying to say that eating a kezayis of ta'am issur doesn't warrant malkus. Therefore, there is no question from Rabbeinu Yosef who says that it is d'oraysa but an issur aseh because that is essentially what the gemara is trying to say - issur but no malkus.

Zevachim 78a - Kezayis for Matzah

The gemara quotes a mishna in challah to prove that ta'am k'ikar is so powerful that on a Torah level it converts the entire mixture (even if it is a minority) to be like it both for an issur to be chayev malkus, and by a mitzvah to qualify as eating a kezayis. The Mishna says that if one would bake matzah with for example 20% wheat flour and 80% rice flour, they could fulfill their mitzvah of matzah with it. The Shulchan Aruch (O.C. 453:2) codifies this, but it is unclear how large of a piece must be eaten. The M.B. explains that there are various opinions regarding the nature of rice flour turning into chometz when mixed with wheat flour, and therefore even if there would be only a small quantity of wheat flour (less than kezayin in achilas p'ras) one could fulfill their mitzvah of matzah, but if the wheat flour were mixed with corn flour there would need to be at least a kezayis of wheat within an achilas p'ras. However, almost no opinion (except for the Ra'avad mentioned in sha'ar hatziyun) requires one to eat multiple kezaysim of the matzah to ensure that he will be eating a kezayis of wheat, rather it is sufficient to simply eat one kezayis. Even the strictest opinion mentioned in the M.B. would hold that if there is a majority of wheat flour to corn flour, we view it as if it were entirely wheat flour so that one can fulfill the mitzvah by eating just a kezayis.

Tosafos asks why the gemara says in Pesachim 115a that one shouldn't eat maztah with marror because the marror which is only d'rabonon will be mevatel the matzah which is d'oraysa. Being that our gemara merely requires the consumption of a kezayis which has the taste of matza, and not to eat a kezayis of matzah, one should certainly be able to fulfill their mitzvah when they eat marror with the matzah? Tosafos answers that specifically by marror which due to its sharpness ruins the taste of the matzah do we consider it to be a problem, whereas the rice flour doesn't ruin the taste of the wheat flour. Secondly, Tosafos answers that the marror ruins the taste of a "kezayis matzah", meaning that if you only eat a kezayis of matzah with the marror you end up tasting less than a kezayis, but if you ate a few kezaysim with the marror you would fulfill your mitzvah.

The Minchas Chinuch (Mitzvah 6 - eating korban pesach) proves from the first answer of Tosafos that one can fulfill their mitzvah of matzah or korban pesach even if they were to eat something else together with the matzah, so long as it wasn't sharp like marror (so long as it is a different type of item, to the exclusion of eating regular meat together with korban pesach). However, the second answer of Tosafos would seem to reject this and hold that even eating an item together with the matzah that isn't sharp could prevent one from fulfilling their mitzvah of matzah - it would all depend on the quantity that they are eating. The M.C. points out that if this were true, the gemara doesn't make sense. The gemara asks on Reish Lakish who holds that one issur is mevatel another indicating that taste isn't d'oraysa to maintain the status of each issur, from the case of mixing wheat and rice flour indicating that taste is strong enough to consider the entire loaf to be matzah. Why doesn't the gemara answer that Reish Lakish is speaking when one one kezayis is eaten and the mishna is speaking when you eat multiple kezaysim? Therefore, the M.C. explains that Tosafos maintains there original position that only the sharpness of the marror can ruin the taste of the matzah, but adds a stipulation that even this is only when one kezayis of matzah is eaten - if multiple kezaysim were eaten, even marror wouldn't be mevatel the matzah. See Minchas Chinuch for a summary of these dinim.

Zevachim 77a - Bringing Sweets on the Mizbeiach

The gemara says that the prohibition of bringing שאור ודבש, yeast and honey, on the mizbeiach only applies when it is being done לריח ניחוח - as an offering. But, if it is being done for the sake of fire wood, meaning not as an offering, there is no prohibition. The Rambam as explained by kesef mishna (issurei mizbeiach 5:3) holds that this only works if it is brought independently but not together with an actual korban. See Minchas Chinuch 117. However, there is a machlokes between the Rabbonon and R. Eliezer in the Mishna if one can burn limbs of a chatas לשם עצים, to be like firewood or whether this is only a heter to bring up yeast and honey on the mizbeiach. We pasken like the Rabbonon that the idea of bringing up for the sake of firewood only works for yeast and honey, but not for other korbanos that don't belong on the mizbeiach. Nevertheless, Tosafos 77b d.h. b'dam suggests that even the Rabbonon would admit that only on kodshim such as a chatas which should be eaten, cannot be brought on the mizbeiach even לשם עצים but the intent "for the sake of firewood" would work for chulin items to be put on the mizbeiach. It is for this reason that we would allow the blood of a korban that gets mixed with non-korban blood to be sprinkled and wouldn't constitute a violation of bringing chulin on the mizbeiach. The rationale seems to be that when something is brought with a korban or is actually a korban, one's intention can't remove that status. Therefore, it would be a violation of burning the meat of a chatas on the mizbeiach. Similary, when one burns the yeast and honey with a korban, it assumes status of a korban so that intent cannot consider it to be merely wood. But when one places chulin on the mizbeiach, since it doesn't belong there, the intent can consider it to be merely wood.

The Minchas Chinuch writes that the sacrificing of yeast and honey לשם עצים only works if it is explicit intent, but if it is done without any intent, it is a violation. It is not clear when one would burn chulin on the mizbeiach without any intent whether we would consider "stam" to be לשם עצים or whether we would require explicit intent לשם עצים to be patur. Tosafos seems to hold that this would also require specific intent.

On an Aggadah note - Sefer HaChinuch suggests that the issur to bring yeast on the mizbeiach is to remind us of zrizus and doing things quickly. The issur to bring honey on the mizebeiach is to teach that a person shouldn't spend their lives running after sweets, rather a person should focus on foods that are healthy for his body and he needs to sustain himself.

ספר החנוך (מצוה קי"ז) - ובענין הרחקת הדבש נאמר אל הילדים רכים כדי לייסרם, שהוא סיבה לדמיון שימעט האדם מלרדוף אחר המאכלים המתוקים לחכו כמנהגג הזוללים והסובאים ימשכו לעולם אחר כל מתוק, ולא יתן לבו כי אם אל המאכלים המועילים לגופו וצריכים למחייתו ושומרים בריאות אבריו. ולזה ראוי לכל בעל שכל לכוין במזונו ושתייתו, לא לכוונת הנאת מישוש הגרון

Zevachim 72a - 73a - Kavua d'oraysa and d'rabonon

The gemara asks why we don't use bitul b'rov in the first case of the mishna when the animal that is assur b'hana'ah gets mixed with the others. The gemara answers that the animal is choshuv therefore too significant to be batul, either because the mishna holds that any davar sheb'minyan isn't batul, or because livestock is inherently significant and not batul. After the gemara establishes that the animal isn't batul b'rov, it continues to ask why we cant separate one by one from the group and bring them as korbanos. The gemara is understanding that after we establish that bitul b'rov doesn't apply to an important and significant item, we should still be permitted to separate one by one and bring them as korbanos each time relying on the statistical majority that the animal we are not sacrificing isn't the forbidden one. To that the gemara responds that it is considered "kavu'ah" so we aren't able to follow the rov. This seems to be a strange case of ka'vua! Normally kavuah applies to a situation where we have things that are established in their place such as kosher and non-kosher butcher shops, but it isn't clear how the concept of kavuah can apply here? The Chochmas Adam (binas adam, sha'ar kakavua 1) explains that the concept of kavuah on the torah level only applies to situations like stores where one buys meat from one of the stores and doesn't know if it was purchased from the 9 kosher or 1 treif. In that case the torah would consider it כמחצה על מחצה and we couldn't rely on rov. However, the kavua in our gemara is very different. In our gemara the gemara means to say that whenever chazal don't allow bitul to take place on an item due to it's significance, we treat the mixture as if it were kavuah. Meaning, not only do we disallow the concept of bitul b'rov on a significant item, but we treat the entire mixture as if is were kavuah and therefore don't even allow one to separate one by one and follow the statistical rov. The gemara continues to ask that we should be able to break the kavua status by sending the animals out and moving them from their established place, but even if we were to do that the Rabbonon were concerned that one may take an animal before moving them. It comes out that the Rabbonon create the concept of kavua on any mixture that contains an important issur on which we won't allow bitul. Once the Rabbonon consider it kavua, they make a second gezeira to be even more machmir than the kavua d'oraysa and we don't allow the kavuah to be broken by moving the animals around because they were concerned that one would take from it before doing that (Tosafos 73b d.h. ela, points out that from the fact that they make a gezeirah that you may come to take it before moving the animals while it is still kavuah, implies that if you were to take before moving the animals it would be d'oraysa. Tosafos rejects this and explains that even taking before moving them would only be d'raobonon). They weren't concerned about this by kavuah d'oryasa since the stores are recognizable in their place and there is no concern that if they permit the meat found in the street that one will come to permit meat that was bought from one of the stores.

Zevachim 71a - Following Rov against reality

The gilyon maharsha references the teshuvos yad eliyahu (eliyahu bar shmuel from lublin - 18th century) who discusses a very interesting question that is pertinent to splitting recovered losses when only part of the losses are recovered. For example in a situation like madoff where there were billions lost and millions recovered, how are those millions split. Is it split proportionately or is it split evenly? The situation that the Yad Eliyahu deals with is animal hides of Jews that were stolen and some of them were retrieved. Those who owned more claimed that they deserved a proportionate return, whereas those who owned less felt that it should be split evenly which could mean that the 10% owner will be fully compensated and the 50% owner would suffer an 80% loss on his investment.

The Mishna says that if a passul chatas gets mixed with kasher ones, they are all left to die. The gemara explains that they are presently kavua and we can't allow bitul b'rov, but discusses why there isn't a possibility of moving them so that we can allow bitul to take place. Tosafos at the end of d.h. afilu asks on the gemara in sanhedrin 79b that when we have someone who deserves a more lenient form of capital punishment who gets mixed up with those who deserve a stricter form, they are all given the more lenient form. Tosafos asks, why don't we say that the person who deserves the more lenient form is batul b'rov and everyone should get the stricter form? Tosafos answers a few different answers:

1. We don't follow rov to be machmir since we will anyway fulfill the mitzvah of carrying out capital punishment on everyone by giving them the lighter punishement.

2. We don't follow rov to do something that we know is not right. If we were to give everyone the stricter punishment, we would for sure be giving someone a stricter punishment that he deserves - דמשום רובא לא נעביד דבר שהוא שקר ודאי, דודאי יש אחד שאינו בר מיתה כלל לפי שלא נגמר דינו

3. At the moment they are considered kavuah and we can't force them to move so that we can follow rov to be machmir on them.

The Yad Eliyahu explains based on Tosafos second answer that we can't simply split proportionately. The rationale to split proportionately would be that we would follow a rov that says that these extra hides belong to Reuven since he owned more of the hides than Shimon. The only way we can follow rov is if the rov could tell us that ALL the hides belong to Reuven. However if Reuven lost 50 hides and 60 of them were retrieved, we couldn't use rov to say that they all belong to Reuven because that is simply not true. Therefore, we cant follow rov. Rather, on each and every hide we say that all the partners own equal shares in it, until the smaller partners are fully compensated and out of the picture so that the remaining hides would be split by the remaining partners. According to this approach, the smaller partners would suffer much less of a loss than the larger partners. But in truth, the Yad Eliyahu is not talking about partners. When there are partners then Reuven would own 60% of every hide retrieved whereas Shimon would only own 10% and they would split all the hides proportionately. The Yad Eliyahu is talking about a case when they aren't partners just that they all had hides stolen and it is unclear who the one's that were retrieved belong to. It is only in that case that we would say they split equally until the smaller partner is fully compensated and then the remaining partners would continue to split the remaining hides.

Zevachim 63a - Eating Kodshim in Heichal

The gemara says that if one would shecht a korban shlomim inside the heichal rather than in the courtyard, it would be valid. The gemara learns this out from the combination of the pasuk that says it should be shechted by the opening of the ohel mo'ed, implying that the ohel mo'ed would even be ideal, just that it can also be shechted by the opening of the ohel mo'ed, in conjunction with the logic of לא יהא טפל חמור מן העיקר - since it can be shechted at the opening of the ohel mo'ed, it can certainly be shechted in the ohlem mo'ed. The gemara asks that based on this approach, it should be obvious that when one is unable to eat kodshim in the courtyard, it can be eaten in the hei'chal (as rashi explains that we have a pasuk saying "in the courtyard of the ohel mo'ed and the logic of לא יהא טפל חמור מן העיקר indicating that the ohel mo'ed would be ideal). Why would R. Yochanan Ben Beseira require a pasuk to teach what seems obvious in sevara? The gemara answers that the logic of לא יהא טפל חמור מן העיקר only works for the shechita which is an avoda and is normal to be done in front of one's master, so the closer the better. But, eating which is not normal to do in front of one's master, the logic would not apply. Rashi explains that no only would the logic "not apply", it would apply in the opposite direction - making it prohibited to eat kodshim in the hei'chal. It is therefore necessary to have a special pasuk to teach that when it is impossible to eat kodshei kodshim in the courtyard because the goyim are bombing it, it can be eaten in the hei'chal.

The obvious question on this gemara is that if the pasuk of פתח אוהל מועד and the logic of לא יהא טפל חמור מן העיקר really apply, it should be ideal to shecht the korban in the ohel mo'ed. Why does R. Yochanan say that bidieved it is kasher, implying that it shouldn't be done lichat'chila? The Rambam (ma'aseh korbanos 5:4) also writes clearly that lichatchila it can be shechted anywhere in the courtyard, but shechting in the hei'chal is only bidieved. Why? It seems that the logic of לא יהא טפל חמור מן העיקר is only on the kashrus of the korban, but not on the action of shechting the korban. Meaning, that the gemara understands that the ideal place for the korban is as the pasuk describes by the opening of the ohel mo'ed in the courtyard, but regarding the kashrus of the korban if shechted elsewhere, it should certainly be kasher if it is shechted in the hei'chal.

Regarding the second halacha that kodshei kodshim can be eaten inside the hei'chal and is learned from a special pasuk - The Rambam (ma'aseh korbanos 10:3) writes - ואם נאכלו בהיכל נאכלו. The Rambam's language is very strange. Clearly the Rambam holds that lichatchila it cannot be eaten in the hei'chal because the case where the gemara permits eating in the hei'chal is only for extenuating circumstances when it absolutely cannot be eaten in the courtyard. The Rambam understands from this that the heter to eat in the hei'chal is only bi'dieved. However, this doesn't seem to make sense because the entire requirement to eat the meat is only lichatchila, but bidieved isn't me'akev! The Even Ha'azel (miluim in the back of kodshim 2, pg. 129b) in responding to R. Tzvi Pesach Frank who asked exactly this question writes that the Rambam seems to disagree with Tosafos in Pesachim 59 and holds that the eating of the meat by the kohanim is me'akev the atonement. Therefore, the Rambam writes ואם נאכלו בהיכל נאכלו, meaning that bidieved the mitzvah of eating is fulfilled even if the kohanim eat it in the heichal and the ba'alim would receive atonement. This approach is also not so me'duayak in the Rambam because he should have written ואם נאכלו בהיכל נתכפרו - that the ba'alim get ATONEMENT. The language of ואם נאכלו נאכלו implies that they aren't fulfilling any mitzvah, just that it is considered "eaten". But it isn't clear what nafka minah this would make!

Zevachim 62a - Measurements of Miz'beiach

The gemara asyas that in the second beis hamikdash they expanded the mizbei'ach, either for practical reasons or because they wanted to incorporate a plumbing system for the wine pouring. The gemara asks how they were able to add to the dimensions of the mizbei'ach, based on the pasuk of הכל בכתב מיד השם עליה שכיל כל מלאכות התבנית, which basically means that all the areas of kedusha and their measurements were taught to Dovid and couldn't be changed. The gemara answers that the area that they sanctified to contain the mizbei'ach that was taught to Dovid was 60 amos. Rashi explains that Shlomo didn't understand the drasha from the pasuk and therefore made the mizbei'ach smaller, but the b'nei ha'gola in the time of the second beis hamikdash darshened it and added on to the size of the miz'beiach. The gemara then explains that many aspects of the mizbei'ach were essential but the length width and height weren't essential and were able to be expanded and contracted as deemed necessary. Therefore, even when they added to the mizbei'ach they didn't take advantage of the entire area to make it as large as possible, because it wasn't necessary for them (it isn't clear to me why rashi has to say that Shlomo wasn't able to darshen the pasuk and didn't know that it was expandable up to 60 amos - why not just say that Shlomo felt that although it could be expanded, he didn't need to make it any larger).

Rashi in chumash (parshas teruma) writes on the pasuk 25:8 - וכן תעשו that in the future when the beis hamikdash would be built they would have to make the vessels similar to those of the mishkan. The Ramban asks on rashi that in divre hayamim 4:1 when it describes the copper mizbeiach made by Shlomo, it says that it was 20 amos by 20 amos, which didn't resemble the one made by Moshe (which was either 5x5 according to the simple reading, or 10x10 according to R. Yehuda 59b)? The Maharal doesn't understand why the Ramban asks this question on Rashi as if Rashi was saying on his own that וכן תעשו is לדורות for the vessels of the Beis HaMikdash. Rashi is sourced in the gemara in shavuos 14b. To answer the Ramban's question the Maharal says that the requirement of וכן תעשו - לדורות is only on movable items, but the mizbeiach which was attached to the ground like the mikdash iteself wasn't bount to this rule. Just as the actual structure of the mikdash and courtyards were very different in dimensions form that of the mishkan, so was the mizbeiach. In truth, rashi never mentions the mizbeiach, only the shulchan, menorah, kiyor.... The Mizrachi answers that the requirement of וכן תעשו is not on the dimensions, rather on the shape and general form.

Zevachim 57b - Harchaka from Aveira and Alos HaShachar

The mishnayos throughout the perek said that for kodshei kodshim and some types of kodshim kalim (Todah and Ayil Nazir) that are eaten for a day and a night, the Rabbonon made a harchaka that one must stop eating by chatzos as a preventative measure to avoid eating after dawn (as rashi quotes 53a from the first mishna in brachos). However, by korban shlomim and other korbanos that can be eaten for 2 days (and the night in between) we don't find the mishna mentioning any harchaka implying that it can be eaten until nightfall.

Tosafos (57b at the end of the perek) writes that when the end time is the beginning of the night it isn't necessary to make a harchaka because the onset of night is obvious and clearly discernible. But when the end time is the onset of day, which is alos hashachar - dawn, it isn't quite as obvious for the average person to discern and therefore necessary to make a harchaka d'rabonon that it couldn't be eaten after chatzos.

Tosafos considers the onset of night to be easily discernible. If it were dependent on sunset, then this would be obvious. But even Tosafos 56a who holds that the blood of the korban becomes passul at sunset, writes explicitly that the end time for eating korban shlomim is tzeis hakochavim - when the stars come out. Therefore, Tosafos considers it easier to recognize 3 average stars coming out and unnecessary to make a harchaka, than it is to recognize dawn. Apparently, the light of dawn is so slight that the average person cannot recognize it. This would be consistent with Rashi in Megilla who writes that the Rabbonon said that every daytime mitzvah should be performed after sunrise, not after dawn, since it is easy to confuse post-dawn with pre-dawn.

Zevachim 56a - Sprinkling Blood After Sunset

The gemara says how do we know that the blood of a korban becomes invalid if it isn't sprinkled on the miz'beiach before "shekiah", and learns out from a pasuk that the blood must be sprinkled the same day that the korban is sacrificed. Rashi explains that we need this special source for a case where the blood was left on top of the miz'beiach to teach that it can become invalid even if לינה occurred at the top of the miz'beiach. Rashi understands that for a typical case where the blood isn't sprinkled the same day, we don't need a special source to invalidate it, since sprinkling can't take place at night and the next day it would certainly be passul like the parts of the animal that are burned on the miz'beiach. Tosafos disagrees with Rashi and says that we need this pasuk to teach that the blood becomes invalid to be sprinkled at sunset, even before צאת הכוכבים which is normally what we consider night. Tosafos explains that even after sunset would still fulfill the requirement of sprinkling by day, we therefore need this pasuk to invalidate any sprinkling after sunset.

In Brachos 26a the Rabbonon consider the time for mincha to be until "erev". Rabbeinu Yona explains that the term "erev" in that context doesn't refer to צאת הכוכבים, rather it refers to sunset. Rabbeinu Yona points to our gemara where the term שקיעת החמה refers to actual sunset with is about 72 minutes prior to צאת הכוכבים. Being that the blood of the evening korban Tamid must be sprinkled before sunset it would follow that in the context of davening mincha, it must be done before sunset. The main activity to validate the korban tamid is the sprinkling of the blood so it would follow that the tefillah of mincha would be dependent on the sprinkling of the blood. Rabbeinu Yona's source for limiting the time of mincha until sunset is completely dependent on learning the definition of שקיעת החמה in our gemara like Tosafos to refer to actual sunset.

The Sha'agas Aryeh (17) has a very long Teshuva where he strongly disagrees with Tosafos and holds that the blood of the korban would only become invalid from being sprinkled at צאת הכוכבים not at sunset. Based on this he writes that the term "erev" in the context of davening mincha is also until צאת הכוכבים, not sunset. He therefore rules that one would be allowed to daven mincha even after shekiha (as chassidim typically do) because even the blood of the Tamid after which mincha was modeled can be sprinkled until צאת הכוכבים. In truth, the Rama (o.c. 233:1) also writes that the time of mincha extends until צאת הכוכבים which can also be read into the term לילה used by the Shulchan Aruch. It is the opinion of the Gr"a (261) that we tend to follow who considers anytime after sunset to be safeik layla, and considers bein hashmashos to last for only 15 minutes or so after sunset at which point it is considered צאת הכוכבים. See the footnotes on Sha'ages Aryeh (footnote 13) where he quotes many opinions who agree with the sha'agas aryeh that mincha can be davened until צאת הכוכבים.

Zevachim 55b - Door of Ohel Mo'ed Being Open

The gemara learns from the fact that the Torah writes by the korban shlomim that it must be slaughtered פתח אוהל מועד that the shechita must take place when the doors are open, not when the doors are shut. The gemara continues to explain that any area where shechita was done had to have some exposure to the inside of the ohel mo'ed, or the u'lam which rashi explains was also called "ohel mo'ed", or to the kodesh ha'kadashim (beis ha'kapores - to allow shechita behind the beis hamikdash in the west). Although the gemara only discusses this requirement regarding the korban shlomim, Tosafos in Yoma 29a writes that the same halacha applies to all korbanos that the area of shechita must be exposed in some way to the inside of the ohel mo'ed.

This halacha of the doors of the ohel mo'ed being open seems to apply only at the time of the shechita not during other avoda, even though the shechita was less avoda-like being that it didn't require a kohein. The Meshech Chochma explains that since shechita was the start of the avoda it had to be in an area where Hashem's presence was visible to connect the avoda to the source of kedusha. Once the avoda begins on the right foot, the remainder of the avoda even it if is more essential follows along - כל העושה על דעת ראשונה עושה ,זבחים בע"ב. It is for this reason that the avoda must begin by day, not by night because daytime is considered when Hashems presence is noticed and revealed. The completion of the avoda such as the burning of the korban could be completed even at night.

Zevachim 53a - 54b - Placement of blood on "horns"

The gemara on 53a brings a machlokes between rebbi and r. elazar b'rabi shimon whether the blood of the korban chatas which required "k'ranos" had to be placed on the 1x1 amah horns that protruded up on the 4 corners of the mizbeiach (r. elazar b'rabi shimon) or if the 4 amos from the top of the horn down had the status of the "horn" and was available for the placing of the blood of the korban chatas. The gemara says that according to rebbi there was a dispute when the blood was placed beneath the horns within the top 4 amos of the miz'beiach, whether it had to be placed on the sharpness of the corner. The issue seems to be dependent on the definition of the term "keren". Certainly it refers to the horn, but can also mean the corner. When the blood is placed on the actual horn it doesn't need to be on the corner, but when it is placed beneath the actual horn, it is a machlokes whether we require it to be placed on the sharpness of the corner (see rashi d.h. u'mar savar, who seems to support this explanation).

In the gemara 54b rav kahana explains that they would make hollow areas within the horns by placing small sticks in that they would pull out when the cement began to dry. Rashi explains that the purpose of these hollow areas was to contain the blood that was sprinkled on it. Tosafos asks on rashi that the blood wasn't placed on top of the horn, rather on the sharpness of the corner so it doesn't seem that the holes were there to absorb the blood? The ya'avetz says that he doesn't understand Tosafos. The gemara on 53a established that all agree the blood can be placed on the horns, in which case it doesn't need to be on the sharpness of the corner. Therefore, rashi is correct that the blood can be placed on the top of the horn and the holes were necessary to help it become absorbed. Perhaps Tosafos understood that although the blood doesn't need to be placed on the sharpness of the corner when it is actually placed on the horn, it would still be ideal to place the blood on the sharpness of the actual horn because that would fulfill both definition of the term "keren" - horn and corner.