and marries his son to her mother, it is permissible, due to the absence of causes for prohibition. If a child is born to each of them, the son of the son would be the maternal uncle of the son of the father, and the son of the father would be the paternal uncle of the son of the son. It is narrated that a man came to Abd al-Malik ibn Marwan and said: "O Commander of the Faithful, I married a woman and I married my son to her mother, so permit us." Abd al-Malik said: "If you inform me of the kinship of your child to the child of your son, I will permit you." The man said: "O Commander of the Faithful, this is al-Uryan ibn al-Haytham whom you have appointed, standing like your sword; if he knows that, then do not permit me." Al-Uryan said: "One of them is the paternal uncle of the other, and the other is his maternal uncle."

Section: If a man marries a woman and marries his son to her daughter or her mother, and the wife of each one of them is consummated by the other, then the first one's act of intercourse obligates him to pay her dower of like value (mahr al-mithl), because it is an act of intercourse of doubt (wat' shubhah). Her marriage to her husband is annulled by it because, through that act, she has become the wife of his son or his father. The dower of the woman who was consummated with is dropped from her husband because the annulment came from her side through her enabling the intercourse and her consent to it, and there is nothing for her husband to claim against the one who had intercourse, as no obligation fell upon him to which he could return. Furthermore, the woman is a participant in the corruption of her marriage through her consent, so nothing became obligatory upon her husband, just as if she were alone in it. It is possible that he is obligated to pay her husband half of her dower of like value, because he corrupted her marriage before consummation, resembling a woman who corrupts his marriage through breastfeeding. The marriage of the one who had intercourse is also annulled, because his wife has become a mother to the one he had intercourse with or a daughter to her, and she is entitled to half of the specified dower. As for the act of the second, it obligates the dower of like value specifically to the woman who was consummated with. If the first is obscure, both marriages are annulled, and each woman is entitled to her dower of like value from the one who had intercourse with her, and no claim of recovery is established for either of them against the other. Half of the specified dower becomes obligatory for the wife of each one of them upon the other, and it does not fall due to doubt.