Yevamos 14:7-8
Yevamos 14:7
Let’s say that two brothers, one of whom has congenital deafness and the other of whom has all his senses, are married to two unrelated women, both of whom have all their senses. If the man with congenital deafness dies, what does his brother with all his senses do? He may perform either yibum or chalitzah. If the man with all his senses dies, what does his brother with congenital deafness do? He marries the widow and can never divorce her (because the Biblical yibum connection trumps his rabbinic ability to divorce).
Yevamos 14:8
Let’s say that two brothers, both of whom have all their senses, are married to two unrelated women, one of whom has all her senses and the other of whom has congenital deafness. If the husband of the woman with congenital deafness dies, what does his brother, married to the woman with all her senses do? He marries her and if he wants to, he may divorce her (but he cannot perform chalitzah). If the husband of the woman with all her senses dies, what does his brother, married to the woman with congenital deafness do? He may perform either yibum or chalitzah.