Ẓihar (a form of divorce by comparison) occurs in two forms. The first is when a man says to his wife, "You are to me as the back of my mother," and remains silent without adding any conditions. In this case, he must offer expiation before engaging in intercourse with her. If he engages in intercourse before performing the expiation, he becomes obligated to offer another expiation. The second form is when a man says to his wife, "You are to me as the back of my mother if I do such and such." In this case, no expiation is required until he actually does the specified action and then engages in intercourse with her. Once he carries out what he swore upon and has intercourse, the expiation becomes mandatory. The prescribed expiation for ẓihar is to free a slave. If he cannot find a slave, he must fast for two consecutive months before resuming relations with his wife. If he is unable to fast, he must feed sixty poor people, giving each person a mudd (a specific measure) of food. If he cannot afford that, he must fast for eighteen days.
Commentary #1