Q: What is the criterion of hijab that a Muslim lady should follow in front of her father-in-law? It is said that ladies can show their beauty to their father in law as they are mahrams, but I know some fathers-in-law who have bad intentions toward their daughters-in-law. What is the law of hijab in this situation?
A: The father in law will be a Mahram to the daughter in law forever, even after separation from the husband or death. Although he is a Mahram, both should dress modestly in front of each other and he should avoid touching her. If the age gap between the two is not very big, it will not be permissible for him to serve as a Mahram for her on journey.
If she senses a bad intention from him, she should never be alone with him and ensure that he never touches her. If he touches her with lust, the Nikah with the son will break immediately. She must necessarily adopt Purdah from a father in-law who has bad intentions.
Moulana Yusuf Laher