There is a person who says that a woman can show her face to her sister’s husband (brother in law), I told him that he is Ghair Muharam but he denies that and asks for proof! So kindly provide us proof from famous Hanafi books with arabic text that the husband of a woman’s sister is ghair muhaharam. If the answer is given in Urdu as well it will be appreciated. Jazakumullah khairan. (please both publish the answer and send it to my mail)
Answer
(Fatwa: 742/268/TL=1432)
Mahram was defined in the books of Fiqh as a person with whom nikah is haram due to kinship, suckling or relations created by marriage:
والمحرم: من لا یجوز لہ مناکحتھا علی التابید بقرابۃ أو رضاع أو صھریۃ (شامی 3:464)
This definition does not apply to brother in law (bahnoi); since the brother in law can marry his sister in law (sali) after giving talaq to his wife or after death of his wife. Therefore, a brother in law is not mahram for his sister in law and she has to observe purdah with him.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband