1) A RELATIVE TESTIFYING FOR THE BENEFIT OF ANOTHER RELATIVE
QUESTION: The Gemara derives from the verse, "Lo Yumsu Avos Al Banim" (Devarim 25:16), that relatives may not testify for each other, and two relatives may not testify together for someone else (see Chart). The Gemara asks that although the verse teaches that a person may not incriminate his relative, it does not teach that a person may not testify for the benefit of his relative. The Gemara gives another source that teaches that a person may not testify even for the benefit of his relative.
What is the Gemara's question? If the verse teaches that a relative may not testify to harm another relative, then it should be obvious that he may not testify for the benefit of his relative! Why is another source needed to teach this law? (CHIDUSHEI HA'RAN)
(a) The CHIDUSHEI HA'RAN answers that indeed this law is learned from a Kal va'Chomer. Nevertheless, the Gemara cites another source for it in accordance with the principle that the Torah often teaches a law explicitly even though it is already taught through a Kal va'Chomer ("Milsa d'Asya b'Kal va'Chomer, Tarach v'Chasav Lah Kra"; Kidushin 4a).
(b) The Chidushei ha'Ran suggests further that the verse is needed to teach that a pair of relatives cannot testify for the benefit of someone else. Even though the verse teaches that they cannot testify to harm someone else, there is no Kal va'Chomer that teaches that they cannot testify to benefit someone else. Perhaps the logic to make such a distinction is that the Torah is more interested in saving people's lives than in killing them (as learned from "v'Hitzilu ha'Edah" (Bamidbar 35:25)), and thus one might have thought that the testimony of two relatives who testify together is accepted in order to save a person from punishment.
(c) The TORAS CHAIM answers based on the Gemara in Bava Basra (159a). The Gemara there teaches that the Torah disqualifies relatives from testifying for each other not because they are suspected of lying, but because of a Gezeiras ha'Kasuv; it is the will of Hash-m, a "Gezeiras ha'Melech," that relatives not testify for each other. The Gemara demonstrates this from the fact that even Moshe Rabeinu and Aharon ha'Kohen were not permitted to testify for each other, even though their integrity was not subject to doubt. Consequently, although the verse teaches that relatives cannot testify to harm each other, one cannot learn from there that they are disqualified from testifying to each other's benefit, since the reason they are disqualified is not because of their sentiments towards teach other. That is why another verse is needed to teach that they cannot testify to benefit each other. (See below, Insights to Sanhedrin 28:3.)
There is a weakness to this answer. Even if there is no logic for why Moshe and Aharon should be disqualified from testifying, there certainly is logic for why relatives are disqualified from giving testimony for each other, in contrast to strangers testifying for each other. The Torah takes into account that some relatives might lie in order to benefit each other, and therefore it makes a blanket ruling, a Gezeiras ha'Kasuv, that no relative may ever testify for another relative. Therefore, the "Gezeiras ha'Melech" is based on the original logic that relatives care for each other, and, therefore, there should be a Kal va'Chomer to teach that a relative may not testify for the benefit of another relative.
2) TESTIFYING FOR A RELATIVE'S WIFE
QUESTION: When Rava traveled to buy parchment (or, according to the Yerushalmi cited by the Margoliyos ha'Yam, when he traveled to a town called "Mizvan Gevili"), he was asked whether a person is allowed to testify for the wife of his step-son. The Gemara concludes that he may not, because of the principle of "Ba'al k'Ishto." Just as one may not testify for his step-son, he may not testify for the wife of his step-son.
Why did they ask specifically about testifying for the wife of one's step-son, and not about testifying for the wife of any of the other relatives mentioned in the Mishnah?
(a) RASHI explains that not only may a person not testify for his relative, he also may not testify about a person whom his relative will inherit. Since the children of all of the relatives mentioned in the Mishnah are also considered relatives about whom one may not testify, it is obvious that one may not testify about the wives of those relatives, since the children of those wives will inherit those wives. However, the son of a step-son is not considered a relative and one may testify for the son of his step-son, and therefore one might have thought that one may testify for his step-son's wife as well, since she will be inherited by her children who are not his relatives for whom he may not testify. (It is assumed that the step-son and his wife have children. If they do not have children, then one may not testify about the wife, because her husband will inherit her, and he may not testify for her husband (his step-son).)
(b) The TALMIDEI RABEINU YONAH explains that it was obvious to the Gemara that one may not testify for any of the wives of the other relatives mentioned in the Mishnah, because of the principle of "Ishah k'Ba'alah." The Gemara's question applies only to "Chorgo," one's step-son, because the Mishnah says that one may testify about the son and son-in-law of his step-son. The Gemara's question concerns the status of a wife. Does the principle of "Ishah k'Ba'alah" make the woman a close relative of her husband, and since one may testify for even the close relatives of his step-son, he may testify for the wife as well? On the other hand, perhaps the wife is considered exactly like the husband, and just as one may not testify for the husband (his step-son), one may not testify for his wife either.
The TORAS CHAIM and KOS YESHU'OS also explain the Gemara this way. Rabeinu Yonah explains that there is no source for Rashi's Halachah that a person cannot testify for a person from whom his own relative will inherit. Rather, a person may testify in such a case. See also MACHANEH EFRAIM (Hilchos Edus #1).
3) THE REASON FOR THE DISQUALIFICATION OF TESTIMONY OF A RELATIVE
QUESTION: The Gemara asks why a person is not allowed to testify for his Arusah if she is not considered his relative with regard to the laws of Kehunah and Yerushah. The Gemara answers that the laws of testimony are not linked to familial relationship, but rather they are linked to "Kiruv ha'Da'as," feelings of emotional closeness, and a man feels close to his Arusah.
The Gemara clearly implies that the laws of testimony depend on emotional considerations and are not merely a "Gezeiras ha'Melech." However, this seems to contradict what the Gemara teaches in Bava Basra (see above, Insights to Sanhedrin 28:1). The Gemara in Bava Basra (159a) teaches that the Torah disqualifies relatives from testifying for each other not because they are suspected of lying, but because of a Gezeiras ha'Kasuv; it is the will of Hash-m, a "Gezeiras ha'Melech," that relatives not testify for each other. The Gemara demonstrates this from the fact that even Moshe Rabeinu and Aharon ha'Kohen were not permitted to testify for each other, even though their integrity was not subject to doubt.
The Gemara there clearly says that the reason why relatives may not testify for each other is not a fear that they will lie due to their emotional closeness, but a Gezeiras ha'Kasuv. How are these two contradictory Gemaras to be reconciled? (The MINCHAS CHINUCH (589:1) leaves this question unanswered and concludes, "Tzarich Iyun Gadol".)
(a) RABEINU YONAH asks the question of the Minchas Chinuch. He answers that the Gemara here means that an Arusah is not disqualified because she is a relative of her Chasan, but because he is Noge'a b'Davar; he feels personal involvement in the case. The Torah is concerned that he will either try to benefit her or to take revenge against her, through giving false testimony, because of their close emotional relationship. Rabeinu Yonah cites support for this explanation from the fact that the Chasan may testify for the relatives of the Arusah, even though, normally, a person may not testify for the relatives of his own relatives mentioned in the Mishnah (27b).
(b) Rabeinu Yonah cites others who answer that the emotional closeness is simply used as a definition for who is considered a relative with regard to testimony. Since a man feels an emotional closeness to his Arusah, she therefore is considered a relative with regard to testimony. Consequently, the man is disqualified from testifying for her even if he is as honest as Moshe Rabeinu. The PILPULA CHARIFTA (3:20:6) offers the same answer.