Musannaf Ibn Abi Shaybah

Hazrat Ibn Abbas (may Allah be pleased with them) says that one who commits adultery with his sister-in-law is guilty of a major sin, but his wife will not become unlawful for him.

Hazrat Zuhri says that if a person commits adultery with his wife's sister (sali), his wife does not become unlawful for him because something unlawful cannot make something lawful unlawful.

Hazrat Ibn Ashwa’ was asked about this matter, so he replied that no unlawful thing can make the lawful unlawful. I have dared to say this, whereas Ibrahim and Hazrat Sha’bi were afraid to say it.

Hasan says that in this case his wife will become forbidden for him.

Hazrat Qatadah says that in the case of committing adultery with one's sister-in-law, the wife does not become forbidden, however, he cannot have intercourse with his wife until the woman with whom he had intercourse completes her waiting period ('iddah).

Hazrat Jabir bin Zaid and Hasan state that in the case of committing adultery with the sister-in-law, the wife will become forbidden.

Hazrat Nakha'i, like Hazrat Qatadah, also holds the view that a woman guilty of fornication will observe the waiting period ('iddah), and that waiting period can last until childbirth.

Hazrat Ata says that committing adultery with a sister-in-law does not make the wife unlawful.

Hazrat Sha'bi says that committing adultery with one's sister-in-law does not make one's wife unlawful (haram) for him.

Hazrat Imran bin Husain says that committing adultery with the sister-in-law will make the wife unlawful.

Hazrat Ibn Abbas (may Allah be pleased with them both) says that committing adultery with the sister-in-law does not make the wife unlawful.