Women with whom matrimony is Haraam
2393. Matrimonial relation is Haraam with women who are one’s Mahram, for instance, mother, sister, daughter, paternal aunt, maternal aunt, niece (one’s brother’s or sister’s daughter) and mother – in – law.
2394. If a man marries a woman, then her mother, her maternal grandmother, her paternal grandmother and all the women as the line ascends are his Mahram, even if he may not have had sexual intercourse with the wife.