Bava Batra

[Once] a certain [man] was dying.  Being asked to whom his wife [was permitted to be married  and] he replied to them, 'She is suitable for the High Priest',  [in considering this case], Raba said: What is there to apprehend?  Surely R. Hiyya b. Abba said in the name of R. Johanan [that] a husband who said, 'I divorced my wife' is believed.  Abaye said to him: But, surely, when R. Isaac b. Joseph came, he said in the name of R. Johanan [that] a husband, who said, 'I divorced my wife', is not believed! — He said to him: Is he not? Surely it has been explained that one  [report speaks] retrospectively and the other  as to the future! Shall we then,  [came the reply], rely upon an explanation?  [Thereupon] said Raba to R. Nathan b. Ammi: Take this into consideration. A certain [person] was known  to have no brothers,  and at the time of his death he declared that he had no brothers, [in considering the case.] R. Joseph said: What is there here  to apprehend? In the first place  it is known that he has no brothers, and secondly  he [himself] has declared at the time of his death that he had none. Abaye said to him: But [people] say that in the countries beyond the sea  there are witnesses who know that he has brothers! — 'Now, at any rate [replied the other, 'they are not before us'.  [Is] not [this case] the same as that of R. Hanina? For R. Hanina said: Shall she  be forbidden [because there are] witnesses at the North Pole!'  Abaye said to him: Shall we relax [the law] in [the case of] a married woman  because  we relaxed [it] in [the case of] a captive woman?  [Thereupon] said Raba to R. Nathan b. Animi: Take this into consideration. THIS IS MY BROTHER', HE IS NOT BELIEVED. And what do the other [brothers] say? If they say. 'He is our brother', why should he [only] take [a share] with him  in his portion and no more?  [If], however, they say, 'He is not our brother', [how will you] explain the latter [clause]: [IF, HOWEVER,] HE ACQUIRED PROPERTY FROM ANOTHER SOURCE, HIS BROTHERS SHARE THE INHERITANCE WITH HIM. [Why should they inherit?] Surely they had declared of him, 'He is not our brother'! — [This law is] required [in the case] only where they say, 'We do not know'. Raba said: This implies [that if a person claims from another], 'You owe me a maneh' and the other replies. 'I do not know, he  is exempt.  Said Abaye: