Gittin

in which case R. Eliezer allowed her to marry anyone except that man and the Rabbis forbade her [to marry at all on the strength of that Get]. What is R. Eliezer's reason? — He puts the condition on the same footing as any other condition. And the Rabbis? — They say that any other condition does not involve an omission in the Get, but this one involves an omission in the Get. And in the Mishnah, where, as we have decided, he means 'except', what is the reason of R. Eliezer? — R. Jannai answered in the name of a certain elder: Because the text says. She shall depart from his house and go and be another man's wife,  which implies that if he permitted her to marry only one other man she is divorced. And the Rabbis? — The word 'man' here means any other man. R. Johanan, however, says that R. Eliezer derived his reason from this verse: Neither shall they [the priests] take a woman put away from her husband.  This shows that even though she is only divorced from her husband [without being permitted to any other man], she is disqualified from the privileges of priesthood, which shows that the Get is valid.  And the Rabbis? — The prohibition of priestly privileges is on a different footing. R. Abba raised the question: What is the rule [if a man uses these words] in betrothing?  The answer is not self-evident whether we adopt the view of R. Eliezer or that of the Rabbis. If we adopt R. Eliezer's view, are we to say that R. Eliezer ruled as he did here [in the case of divorce] only because this is indicated in the Scripture, but in the case of betrothal we require an effective acquisition?  Or shall we say that R. Eliezer applies the principle of she shall depart and be [married]?  Again, if we adopt the view of the Rabbis, are we to say that the Rabbis ruled as they did here [in the case of divorce] only because we require a 'cutting off',  but in the other case any kind of acquisition is sufficient, or shall we say that they apply the analogy of 'she shall depart and be'? — After stating the problem he himself solved it, saying: Whether we adopt the view of R. Eliezer or that of the Rabbis, we require that the analogy of 'she shall depart and be' should hold good. Abaye said: If we can assume that the answer of R. Abba was sound, then if Reuben came and betrothed a woman with a reservation in favour of [his brother] Simeon, and then Simeon came and betrothed her with a reservation in favour of Reuben, and both of them died, she contracts a levirate marriage with Levi, [the third brother] and I do not call her 'the wife of two dead',  the reason being that the betrothal of Reuben was effective but the betrothal of Simeon was not effective.  And in what circumstances would she be the wife of two dead?  — If, for instance, Reuben came and betrothed her with a reservation in favour of Simeon and then Simeon came and betrothed her without any reservation, in which case the betrothal of Reuben availed to make her forbidden to all other men and the betrothal of Simeon to make her forbidden to Reuben. Abaye raised the question: If he said to her, 'You are hereby permitted to any man except Reuben and Simeon', and then said 'to Reuben and Simeon' what is to be done? Do we say that [by these words] he permits what he had forbidden,  or are we to say that he both permits what he had forbidden and forbids what he had permitted?  And assuming the answer to be