The Sufficient (Vol 5) · Hadith 1578 (#Ḥadīth #6)
Chapter 74 | 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- عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ سَهْلِ بْنِ زِيَادٍ عَنِ ابْنِ مَحْبُوبٍ عَنْ عَلِيِّ بْنِ رِئَابٍ عَنْ زُرَارَةَ قَالَ سَأَلْتُ أَبَا جَعْفَرٍ عَنْ رَجُلٍ زَنَى بِأُمِّ امْرَأَتِهِ أَوْ بِأُخْتِهَا فَقَالَ لا يُحَرِّمُ ذَلِكَ عَلَيْهِ امْرَأَتَهُ إِنَّ الْحَرَامَ لا يُفْسِدُ الْحَلالَ وَلا يُحَرِّمُهُ.
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 , 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.’”
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).