Yevamot

If the brother of the levir had betrothed the sister of the widow who was awaiting the levir's decision,  he is told, so it has been stated in the name of R. Judah b. Bathyra, 'Wait  until your brother has taken action;'  and Samuel said, 'The halachah is in accordance with the ruling of R. Judah b. Bathyra'.  The other  asked him: 'What [objection could there be] if the statement  be attributed to Rab?  Is it the contradiction between the two statements of Rab?  Surely it is possible that these Amoraim  are in dispute as to what was the opinion of Rab!' — Since this ruling was stated with certainty in the name of Samuel, while as to Rab's view [on the matter] Amoraim differ, we do not ignore  the statement attributing it with certainty to Samuel in favour of the one  which involves Amoraim In a dispute as to the opinion of Rab. Said R. Kahana: I reported the statement  in the presence of R. Zebid of Nehardea, when he said: You teach it thus;  our version is explicit:  'Rab Judah stated in the name of Samuel, "If a woman awaiting the decision of the levir died, [the levir] is forbidden to marry her mother", from which it naturally follows that he is of the opinion that a levirate bond exists'.  Samuel is here consistent; for Samuel said, 'The halachah is in accordance with the view of R. Judah b. Bathyra'. Said [both statements  are] necessary. For had he only stated, 'A levirate bond exists', it might have been assumed to refer to the case of one levir only  but not to that of two,  hence we are taught  [that the Same law applies also to two]. And if it had only been stated, 'The halachah is in accordance with the opinion of R. Judah b. Bathyra', it might have been assumed [that the levirate bond is in force] while the widow  is alive but that after her death the bond is dissolved, hence we are taught  that the levirate bond Is not dissolved automatically. MISHNAH. IF THERE WERE TWO BROTHERS AND ONE OF THEM DIED,  AND THE SECOND PERFORMED THE LEVIRATE MARRIAGE WITH HIS [DECEASED] BROTHER'S WIFE, AND AFTER A [THIRD] BROTHER WAS BORN THE SECOND DIED,  THE FIRST  IS EXEMPT  ON ACCOUNT OF HER BEING THE WIFE OF HIS BROTHER WHO WAS NOT HIS CONTEMPORARY', WHILE THE SECOND IS EXEMPT AS HER RIVAL.  IF HE  ADDRESSED TO HER  A MA'AMAR AND DIED,  THE SECOND MUST PERFORM THE HALIZAH  BUT SHE MAY NOT BE TAKEN IN LEVIRATE MARRIAGE. R. SIMEON SAID:  HE  MAY EITHER TAKE IN LEVIRATE MARRIAGE WHICHEVER OF THEM HE DESIRES  OR HE MAY PARTICIPATE IN THE HALIZAH WITH WHICHEVER OF THEM HE DESIRES. GEMARA. R. Oshaia said: R. Simeon disputed the first case also  Whence is this inferred? From the existence of  a superfluous Mishnah. For in accordance with whose view was it necessary to teach the clause of the first [Mishnah]? If it be suggested, [according to that] of the Rabbis, [it may be retorted]: If when the levirate marriage had taken place first and the birth  occurred afterwards, in which case he,  found her  permitted,  the Rabbis nevertheless forbade her,  is there any need [for them to specify prohibition in the case where] the birth  occurred first and the marriage took place afterwards!  Consequently  it must have been required [in connection with the view] of R. Simeon; and the first [Mishnah] was taught in order to point out to you how far R. Simeon  is prepared to go  while the last Mishnah was taught in order to show you how far the Rabbis  are prepared to go. It would, indeed, have been logical for R. Simeon to express his dissent in the first case, but he waited for the Rabbis to conclude their statement and then he expressed his dissent with their entire statement. How, in view of what has been said,  is it possible according to R. Simeon to find a case of 'a wife of his brother who was not his contemporary'?  — In the case of one brother who died and a second brother was subsequently  born;  or also in the case of two brothers  where the second has neither taken the widow in the levirate marriage nor died. One can well understand [R. Simeon's reason]  where the levirate marriage  took place first and the birth  afterwards, for in this case he found her permitted;  where, however, the birth occurred first and the levirate marriage took place afterwards,  what [reason [could be advanced]?  -He holds the opinion that a levirate bond exists  and that such a bond is like actual marriage. R. Joseph demurred: If R. Simeon is in doubt as to whether in the case of a 'levirate bond' and a 'ma amar' combined the widow should or should not be regarded as married, need there be any [doubt in the case of] a 'levirate bond' alone?  Whence is this known?  — We have learned: In the case where three brothers were married to three women who were strangers [to one another] and, one of the brothers having died, the second brother addressed to her,  a ma'amar and died, behold these  must perform halizah with, but may not marry the [surviving] levir; for it is said in the Scriptures, And one of then die [etc.], her husband's brother shall go in unto her,  only she  who is tied to one levir,  but not she who is tied to two levirs.  R. Simeon said: He  may take in levirate marriage whichever of them he pleases  and submits to the halizah of the other.  He must not take both widows in levirate marriage since it is possible that a levirate bond exists  and thus the two sisters-in-law  would be coming