One’s Marriage with a Mother or Sister of a Woman after out of Wedlock Conjugal Relation With Her Or going to Bed with One’s Mother-in-Law Or Stepdaughter

6. A number of our people have narrated from Sahl ibn Ziyad from ibn Mahbub from ibn Ri’ab from Zurarah who has said the following: “This is concerning my question before abu Ja‘far عليه السلام, about the case of a man who goes to bed with the mother of his wife or her sister. He (the Imam) said, ‘This does not make his wife unlawful for him; unlawful does not destroy or make lawful ones unlawful.’”