Baba Basra 128a - Pesulei Eidus

An Overview of Halachos of p'sulei eidus

Often people are mesader kiddushin and aren't sure who is passul to sign together on a kesubah, or be witnesses under the chupah. These are the halachos from Choshen Mishpat (33) in a nutshell:

A rishon b'rishon includes all immediate relatives in all directions such as a father/mother, son/daughter, brother/sister and even a wife.

A rishon b'sheini is one level removed such as a man to his brother's son (nephew), or man to his uncle.

A sheini b'sheini is one level removed on both sides such as first cousins (parents are brothers so they are rishon b'rishon, their children are sheini b'shein).

A rishon b'shlishi would refer to two levels removed such as a man to his brother's grandson, or to his great uncle (father is rishon, grandfather is sheini, grandfather's brother is shlishi).

Therefore: Father to son is rishon b'rishon. Grandfather to grandson is rishon b'sheini. Great grandfather to great grandson is rishon b'shlishi.

In terms of when we also invalidate a spouse: For a rishon b'rishon we apply בעל כאשתו (husband and wife are the same) even two times so that the husbands of two sisters are considered rishon b'rishon. For rishon b'sheini we definitly apply בעל כאשתו once, but there is a machlokes whether we apply it twice. For a sheini b'sheini we definitely apply ba'al k'ishto, but only once. For a rishon b'shlishi there is a machlokes rishonim (rashbam and tosafos 129a) whether it is passul at all. Even those who say that it is passul (rabbeinu tam and b'hag both hold that it is passul but argue if it is d'oraysa or d'rabonon) would agree that we don't say בעל כאשתו at all. The Rama holds that we only apply בעל כאשתו twice for a rishon b'rishon, we apply it once for a rishon b'sheini and a sheini b'sheini (but two people who are sheini b'sheini even with two בעל כאשתו such as the husbands of two first cousins, shouldn't sign a contract together because we are worried about a beis din mistakingly invalidating the contract), but for a rishon b'shlishi even those who are machmir (Rabbeinu Tam), admit that we don't apply בעל כאשתו at all.

It is important to point out that the concept of בעל כאשתו only applies to make the wife invalid to be testified about by the husband's relative, and make the husband invalid to be testified about by the wife's relatives (machlokes rishonim whether we apply this in both direction m'doraysa or only m'drabonon - see aruch hashulchan 33:1). But, בעל כאשתו does not create a relationship to make the wife's relatives assur to testify for the husbands relatives. The halacha is clear in shulchan aruch that the father of the husband can testify for the father of the wife (we don't even count it as a sheini b'sheini as a result of viewing the husband and wife as a rishon b'rishon, certainly we don't view it as a rishon b'rishon by viewing the husband and wife as one entity).

Now, Mar Bar Rav Ashi says that a grandfather can testify for a grandson and visa versa, but the gemara says we don't pasken like him. Rashbam explains that a grandfather to a grandson is a rishon b'shlishi. The maharsha already points out that this is inaccurate, because a father to a son is a rishon b'rishon, so that a grandfather to grandson is a rishon b'sheini! The maharsha explains that the rashbam is trying to justify the position of mar bar rav ashi. The fact that there is a large generation gap "איתפלג דרא", causes mar bar rav ashi to regard it as a rishon b'shlishi to permit one to testify for the other. Tosafos uses this logic to explain how mar bar rav ashi would justify saying that two first cousins cannot testify for one another (sheini b'sheini), but a grandson can testify for a grandfathter - איתפלג דרא make is permissible.

The Sm"a (33:15) writes that since a husband and wife is considered a rishon b'rishon, according to Rashbam and Rambam that a rishon b'shlishi is permitted, a husband may testify for his wife's grandfather because it is a rishon b'shlishi. The Taz argues with the Sm"a because the grandfather to his son would be rishon b'rishon, to his grandaughter would be rishon b'sheini, so to the husband would be a rishon b'sheini with one בעל כאשתו which would be assur according to everyone. See the nesivos who quotes the machlokes. Why does the sm"a consider this to be a rishon b'shlishi, rather than a rishon b'sheini with a בעל כאשתו? The Gr"a answers based on Tosafos. Although we don't pasken like mar bar rav ashi, we learn from him an important lesson. The larger the generation gap, the more likely we are to be matir based on איתפלג דרא, even if it should technically be assur. Therefore, since a wife is 2 generations removed from her grandfather, we don't consider the husband with the wife's grandfather to be a rishon b'sheini with a בעל כאשתו, rather we consider it a rishon b'shlishi. Just as mar bar rav ashi considers a grandfather and grandson to be a rishon b'shlishi, we reject that, but if we add a בעל כאשתו, then we also consider it a rishon b'shlishi.