Bava Batra

you gave him to me as a gift, [but] if you wish, take an oath  and you will get him back';  and [the first] took the oath; [the latter] is not allowed to retract.  What does he teach us?  [The obvious principle underlying the law] has [surely] been taught [elsewhere]:  [If one of the litigants] said to the other,  'I have full confidence  in my father,  I have full confidence in your father, I have full confidence in three oxherds',  R. Meir says, he may retract,  and the Sages say he may not!  He  teaches us this: That the dispute  [relates also to the case] where [a litigant declared], 'I will give it to you'  and [that] the halachah is in accordance with the words of the Sages. R. Abba sent to R. Joseph b. Hama: The halachah is that slaves may be seized [from orphans, in payment of a debt incurred by the father].  R. Nahman. however, said they may not be seized. R. Abba sent to R. Joseph b. Hama: The halachah is that [a relative in the] third [degree] is qualified [to act as witness for or against a relative] in the second [degree].  Raba said: Also [for, or against a relative] in the first [degree]  also. Mar, son of R. Ashi permitted [a grandson to act as witness] for his father's father. The law, [however], is not in accordance with [the view of] Mar, son of R. Ashi. R. Abba sent to R. Joseph b. Hama: If a person possessed evidence  in one's favour [in the matter of a plot of] land, before he became blind, and [then] became blind, he is disqualified.  Samuel, however, said: He is permitted [to give evidence], [since] it is possible for him to gauge [the extent of] its boundaries; but [in the case of] a cloak [he is] not [to be admitted as witness].  R. Shesheth said: Even [in the case of] a cloak [his evidence is admissible, for] it is possible for him gauge the measurements of its length and of its breadth; but not [in the case of] a bar of metal. R. Papa said: Even [in the case of] a bar of metal, [for] it is possible for him to gauge its weight. An objection was raised: 'If a person possessed evidence  affecting another before he became his son-in-law, and, [subsequently,] he became his son-in-law, [or if that witness] had the faculty of hearing and became deaf, the faculty of seeing and became blind, sane and became insane, he is disqualified [from giving evidence]. If, however, he possessed evidence affecting him before he became his son-in-law, and when he became his son-in-law, his daughter died; [or if he] had the faculty of hearing, became deaf, and regained his hearing; [or if he] had the faculty of Seeing, became blind, and regained his eyesight; [or if] he was sane, became insane, and regained his sanity, [in all these cases] he is qualified [to act as witness]. This is the general rule: Whenever his beginning  or his end  was under a disqualification, he is disqualified, [but whenever] his beginning and his end [find him] in a suitable condition, he is permitted [to give evidence].