Study Yevamot folio 20B with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
The Talmud answers: That stands to reason, since betrothal takes effect with those women who are forbidden and with whom he would be liable for the violation of a prohibition. That is, if a man betroths a woman who is forbidden to him and with whom he would be liable for the violation of a prohibi
Rava raised an objection to the explanation of Rav: It is taught in a baraita with regard to a prohibition resulting from a mitzva and a prohibition stemming from sanctity that if he has sex with such a woman or performs ḥalitza with her, her rival wife is exempt, even though it was prohibited for
Rava raised the objection and he resolved it: The baraita teaches it disjunctively; it did not all deal with the same case. When the baraita says: has sex with her, it is referring to a prohibition resulting from a mitzva. If one has sex with a yevama prohibited to him by rabbinic law, since by
Rava raised an objection from that which was taught in the Tosefta (Yevamot 11:3): A man with crushed testicles or with other wounds to his genitals or one whose penis has been severed, one who is a eunuch caused by man and not from birth or by disease, or an elderly man, all of whom are incapable
The inverse is also true: If the brothers died childless, and the infertile men proceeded to perform levirate betrothal with their wives, or gave a bill of divorce, or performed ḥalitza, whatever they did is done and took effect. And if they had sex with their yevama, they thereby acquired the yeva