Yevamot

'One who is Rabbinically regarded as a robber  is eligible to be a witness in matrimonial matters;  one, however, who is Biblically regarded as a robber is ineligible to act as witness in matrimonial matters;  would it then be necessary to assume that R. Manasseh holds the same opinion as R. Judah?  - R. Manasseh can answer you: My statement may be reconciled even with the view of the Rabbis, but the reason of the Rabbis  here is the same as that of Raba. For Raba said, 'A man is his own relative and consequently  no man may declare himself wicked'. Must it then be assumed that R. Joseph  is of the same opinion as R. Judah?  — R. Joseph can answer you: 'My Statement may be in agreement even with the view of the Rabbis, but matrimonial evidence  is different, since the Rabbis relaxed the law in its case;  and it is R. Manasseh who adopted the view of R. Judah'. 'I KILLED HIM' etc., 'WE KILLED HIM' … MAY MARRY etc. What is the practical difference between 'I killed him' and 'we killed him'?  — Rab Judah said: [Our Mishnah speaks of the case] where he said, 'I was present together with his murderers' — 12 Has it not, however, been taught: They said to R. Judah, 'It once happened that a robber when led out to his execution in the Cappadocian Pass  said to those present,  "Go and tell the wife of Simeon b. Kohen that I killed her husband when I entered Lud" [others Say: When he entered Lud], and his wife was permitted to marry again'!  He answered them: Is there any proof from there? [It was a case] where he said, 'I was present together with his murderers'.  But it was stated, 'a robber'! — He was apprehended on account of robbery.  But it was stated, 'led out to his execution'! — [He was sentenced by] a heathen court of law who executed without due investigation. MISHNAH. A SAGE WHO HAS PRONOUNCED A WOMAN FORBIDDEN TO HER HUSBAND BECAUSE OF A VOW  MUST NOT MARRY HER HIMSELF.  IF, HOWEVER, A WOMAN MADE A DECLARATION OF REFUSAL  OR PERFORMED HALIZAH IN HIS PRESENCE, HE MAY MARRY HER, SINCE HE [WAS BUT ONE OF THE] BETH DIN. GEMARA. This implies that if he had disallowed her vow, be would have been permitted to marry her!  What then are the circumstances?  If [he acted] alone, could one disallow a vow? Surely  R. Hiyya b. Abin said in the name of R. Amram that it was taught: The disallowance of vows is to be carried out by three! If, however, three were Present, would they be suspected? Surely we learned, IF, HOWEVER, A WOMAN MADE A DECLARATION OF REFUSAL OR PERFORMED HALIZAH IN HIS PRESENCE, HE MAY MARRY HER, SINCE HE [WAS BUT ONE OF THE] BETH DIN!-The fact is that [he acted] alone, and  as R. Hisda said in the name of R. Johanan, 'By a fully qualified individual',  so here also it is a case of one fully qualified individual. IF A WOMAN MADE A DECLARATION OF REFUSAL, OR PERFORMED HALIZAH etc. The reason, then,  is because [he was one of a] Beth din,  but had he been one of a group of two only. would he not [have been permitted]? Wherein, then, does this case differ from the following concerning which it was taught:  If witnesses signed on [a document relating to] a purchased field or on a letter of divorce, the Rabbis do not apprehend such collusion!  — It is this very thing that he taught us,  viz., that the opinion of him who said that a declaration of refusal may be made in the presence of two is to be rejected and that one is to infer  that a declaration of refusal must be made in the presence of three. The question was raised: If he  married her  must he part from her? R. Kahana said: Though he married, he must part from her. R. Ashi said: Once he has married, he need not part from her. R. Zuti at the School of R. Papa recited [a teaching] in accordance with the opinion of him who said that if he  married her  he need not part from her. Said the Rabbis to R. Ashi: Is this  a tradition or a matter of opinion? He answered them: It is a Mishnah: If a man is suspected of intercourse with a slave who was subsequently emancipated, or with a heathen who subsequently became a proselyte, lo, he must not marry her; if, however, he did marry her the marriage need not be dissolved. Which proves