Nazir 20b - Makos Mardus

The mishna is really on 23a, but since Tosafos is here i will speak about it here.

We find 2 types of malkus that are m'drabonon, one is a makos mardus for doing an issur d'rabonon, and the other is a kefiya to be "מכין אותו עד שתצא נפשו" like we find in kesubos to force the fulfillment of mitzvas aseh. Tosafos has a safeik whether the unlimited malkus of עד שתצא נפשוis for a case where we are trying to push him to do mitzvos, so that the "limit" will be either when he does the mitzvah or when he dies, but when we are using malkus as a punishment for the violation of an issur we would model the amount of malkus after the d'oraysa and limit it at 40, or do we punish an unlimited amount of malkus even for the violation of a d'rabonon. The Mahratz chiyus quotes from the teshuvas rashbam that we only implement the unlimited malkus to force people to fulfill mitzvas aseh, but for the violation of an issur we would not hit him עד שתצא נפשו.

However, he points to a Rambam (Laws of Chometz 6:12) who writes:
ומי שאכל מצה בערב הפסח מכין אותו מכת מרדות עד שתצא נפשו

There are 2 problems with this Rambam, first that we don't hit עד שתצא נפשו for violating an issur, and second we don't hit עד שתצא נפשו post facto. The mahratz chiyus deals with the first question by explaining that the issur of eating matzah on erev pesach is linked to the mitzvah to eat matza at night l'teiavon, therefore eating matzah on erev pesach is essentially a bitul mitzvas aseh that we can hit him for עד שתצא נפשו. However, he never deals with the second question which is that the Rambam sounds like we punish him for the eating of matzah on ereve pesach, after he already ate it, not only to prevent him from eating. How can we punish him so severely after the fact has been done? Perhaps the Rambam holds that just as one can force to fulfill a mtizvas aseh such as succah and lulav, we can also force עד שתצא נפשו to fulfill the mitzvah of eating matzah l'teiavon. Therefore, if one has shown that he is not going to eat matzah l'teiavon by eating it on ereve pesach, we force him to stop eating it and accept on himself not to eat for the rest of the day, and we are entitled to force him by hitting him עד שתצא נפשו .

Another chiddush we see from this Rambam is that eating matzah l'teiavon is not just a hidur mitzvah (as the rashbam says in pesachim 99b) because we wouldn't hit him עד שתצא נפשו for a hidur mitzvah (at least i am not aware of any sources that indicate that we would). Rather the Rambam holds that it is essential to the primary chiyuv of eating matzah, that it be eaten l'teiavon.