Yevamot

Let her  continue to live with him in any case. For if [a deaf woman] is acquired  then she is of course acquired,  and if she is not acquired,  then she is a mere stranger.  And should you argue, 'why should the minor wait until she grows up and then performs halizah? Let her  continue to live with him [for the same reason  that] if she is [properly] acquired  then she is of course acquired,  and if she is not acquired,  then she is a mere stranger';  if so [it could be retorted] whereby should the deaf [widow] be released! R. Shesheth said: Logical deduction leads also to the interpretation R. Hisda imparted to Rab's ruling.  For it was taught: If two brothers were married to two orphan sisters,  a minor and a deaf woman, and the husband of the minor died, the deaf widow is released by means of a letter of divorce  while the minor waits until she is of age, when she performs halizah.  If the husband of the deaf woman dies, the minor is released by a letter of divorce  while the deaf widow is forever forbidden [to marry again].  If, however, he cohabited with the deaf widow  he must give her a letter of divorce and she  becomes permitted [to marry any other man].  Now, if you grant that a deaf wife is partially acquired  [and that concerning] a minor [it is doubtful whether] she is [fully] acquired  or not acquired [at all], one can well see the reason why when he cohabited with the deaf widow he gives her a letter of divorce and she becomes permitted [to marry any other man]. For you may rightly claim that in any case [she becomes permitted]. If the minor is acquired,  [the deaf widow] is rightly released as his wife's sister;  and if she is not acquired [at all] he has quite lawfully contracted with her  the levirate marriage.  If you contend, however, [that concerning] a deaf woman [it is doubtful whether] she is acquired  or not acquired [at all], and that a minor is partially acquired,  [the difficulty arises] why should the deaf widow, if he cohabited with her and gave her a letter of divorce, be permitted [to marry again] when the cohabitation with her was unlawful,  and an unlawful cohabitation does not release a woman?  — It is possible that this statement represents the view of  R. Nehemiah who ruled that an unlawful cohabitation exempts [a widow] from halizah. If [this statement represents the view of] R. Nehemiah read the final clause: 'If a man was married to two orphans,  one of whom was a minor and the other deaf, and died 'and the levir cohabited with the minor and then cohabited with the deaf widow, or a brother of his cohabited with the deaf widow,  both are forbidden to him.  How do they obtain redress? The deaf woman is released by a letter of divorce  while the minor waits until she is of age 'when she performs halizah'.  Now, if you grant  that a deaf wife is partially acquired [and that concerning] a minor [it is doubtful whether she is fully] acquired or not acquired [at all],  and [that the opinion in this statement] is that of the Rabbis,  one can well understand the reason why  'the minor  waits until she is of age, when she performs halizah', since [otherwise]  he might cohabit with the deaf widow first,  and the [subsequent] cohabitation with the minor would [thereby] be rendered an unlawful cohabitation.  If you contend, however, [that the opinion in the statement is that of] R. Nehemiah,  surely he [it may be objected] ruled that an unlawful cohabitation does exempt!  Consequently it must be concluded [that the opinion in the statement is that of] the Rabbis. Our point is thus proved. R. Ashi said: From the first clause  also it may be inferred that [the opinion expressed] is that of the Rabbis. For it was stated, 'If,  however, he cohabited with the deaf widow he must give her a letter of divorce and she becomes permitted [to marry any other man]', but it was not stated,  'If he cohabited with the minor, he must give her a letter of divorce and she becomes permitted'!  — If this is all, there is not much force in the argument; since in respect of the deaf widow for whom no lawful redress is possible  mention had to be made of redress obtained through a forbidden act,  but concerning a minor, for whom lawful redress is possible,  no redress obtainable through a forbidden act was mentioned. MISHNAH. IF A MAN WHO WAS MARRIED TO TWO ORPHANS WHO WERE MINORS DIED, AND THE LEVIR COHABITED WITH ONE,  AND THEN HE ALSO COHABITED WITH THE OTHER,  OR A BROTHER OF HIS COHABITED WITH THE OTHER,