Yevamos 3:7-8

Yevamos 3:7

Let’s continue with the case of three brothers, two of whom are married to sisters and one of whom is married to an unrelated woman. (a) One of the brothers married to a sister died and the brother married to the unrelated woman married the widow. Then the wife of the other brother (the widow’s sister) died, and then the brother married to the unrelated woman (who also married the widowed sister) died. The twice-widowed woman is permanently prohibited to the remaining brother because she had once been prohibited (as a yevama since she was his wife’s sister at the time). (b) Let’s say that one of the brothers married to a sister divorced her and then the brother married to the unrelated woman died, then the divorced brother married her and he subsequently died. This case is what the Sages meant when they said (in mishna 1:1) that if any prohibited woman dies or is divorced, her co-wives become permitted.

Yevamos 3:8

Regarding all 15 of the prohibited types of women (in mishna 1:1), if the validity of a marriage or divorce in is question, the co-wives perform chalitzah but not yibum. A marriage in question is, for example, if the man threw the woman the money or document to effect the marriage and it is unclear whether it landed closer to him or to her. An example of a divorce in question is if the husband wrote the get in his own hand but there are no witnesses, or if there are witnesses but no date, or a date but only one witness.