Mahram refers to all those persons with whom marriage is not permissible on
a permanent basis Below is list detailing those with whom Nikah is not
permissible on a permanenet basis.
Persons with whom Nikâh is Harâm forever
1. Marriage with one’s children, grand-children, great grand-children, etc.
is not permissible. Nor is marriage with one’s parents, grand-parents,
maternal grand-parents, etc. permissible.
2. Marriage with one’s brothers, uncles and nephews is not permissible.
According to the Sharî’ah, a brother is one whose mother and father is the
same, or they have one father but two mothers, or one mother but two
fathers. They are all brothers. But if the father is different, and the
mother is also different; that person will not be a brother. Nikâh with him
will be valid.
3. Marriage with one’s son-in-law is not permissible. This is irrespective
of whether the daughter is already living with him or not. In all cases,
nikâh with him is harâm.
4. A girl’s father passed away. Her mother married another person. However,
before the mother could even live with her new husband, she passed away or
he divorced her. In such a case, the girl can marry this step-father of
hers. However, if the mother lived with him, it will not be permissible for
this girl to marry him.
5. Nikâh with one’s step-children is not valid. In other words, if a man has
several wives, then one of the wives cannot marry the children of the
co-wives. This is irrespective of whether she had lived with her husband or
not. Nikâh with these children is prohibited under all circumstances.
6. It is not permissible for a woman to marry her father-in-law or even the
father or grand-father of her father-in-law.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai