to keep her marriage, he should separate from the one he did not have relations with by a single pronouncement of divorce (5), then leave the one he had relations with until her waiting period (idda) expires, then marry her; because we are not secure that she was not the second one, in which case he would have had relations with her within an invalid marriage. For this reason, we considered the expiration of her waiting period necessary. It is possible that it is permissible for him to contract with her immediately, because the lineage is linked to him, and this is not protected from his seminal fluid. If he prefers to marry the other one, he should separate from the one he had relations with by a single pronouncement of divorce, then wait for her until her waiting period expires, then marry her sister. The third category is if he had relations with both of them; he may not marry either of them until he separates from the other and her waiting period expires from the time of his separation from her, and the waiting period of the other expires from the time he had relations with her. If one of them, or both of them, bears a child by him, the lineage is linked to him because it is either from a valid marriage or an invalid one, and in both cases, the lineage is confirmed. If he does not wish to marry either of them, he should separate from both of them with a single pronouncement of divorce each.

Section: As for the dowry, if he has not had relations with either of them, one of them is entitled to half the dowry. We do not know which of them is entitled to it, so they should reach an agreement on it. If they do not, lots are drawn between them, and it belongs to the one whose lot is drawn, along with her oath. Abu Bakr said: My preference is that the dowry lapses if he is compelled to divorce before consummation. If he had relations with one of them, lots are drawn between them; if it falls to the one he did not have relations with, she receives half the dowry, and the one he had relations with receives the dowry of a peer (mahr al-mithl) for what he made lawful of her private parts. If it falls to the one he had relations with, the other gets nothing, and the one he had relations with gets the entire specified dowry. If he had relations with both of them, one is entitled to the specified dowry and the other to the dowry of a peer; lots are drawn between them for this, if we say that what is mandatory in an invalid marriage is the dowry of a peer. If we say that the specified dowry is mandatory in it, then it is mandatory here for each of them (7).

Section: Ahmad said: If he marries a woman, then marries her sister, and has relations with her, he must keep away from his [first] wife