Tractate Yevamot - Chapter 14 - Mishnah 7

If two brothers, one of whom was deaf and the other of sound senses, were married to two strangers who were of sound senses, and the deaf brother, the husband of the woman who was of sound senses, died, what should the brother of sound senses, the husband of the woman of sound senses, do? He either performs halitzah or yibbum. If the brother of sound senses, the husband of the woman who was of sound senses, died, what should the deaf brother, the husband of the woman who was of sound senses, do? He must marry her and he may never divorce her.