Is it permissible for a wife who wears the niqab to remove it while working in the house in front of her husband’s brothers and his sister’s husband, knowing the hadith "Al-Hamwu al-Mawt" (The in-law is death), due to the difficulty of performing household chores such as cooking and kneading while wearing the niqab, and to avoid harm that might befall her husband’s elderly parents if she were to leave the house?

A woman must be careful to observe complete hijab (definition) in front of non-mahram (definition) men. A sister's husband and non-mahram brothers are not among the exempted mahrams mentioned in Allah's (the Most High) saying: "And not expose their adornment except to their husbands or their fathers" {An-Nur: 31}. Hijab is further from temptation and more conducive to purity of hearts, as Allah (the Most High) says: "And when you ask [his wives] for something, ask them from behind a partition. That is purer for your hearts and their hearts" {Al-Ahzab: 53}. Scholars have agreed on the obligation of covering the head, neck, arms, and legs from non-mahram men. They differed regarding covering the face and hands, and the preponderant opinion is that it is obligatory to cover them as well.