The Ruling on Marrying the Wife of the Wife's Father

Question :

There are two men, the first married the daughter of the second, then the mother of the daughter the wife of the second died and he married another, then the man died. My question is: Is it correct for the first man to marry the wife of his wife's father? And what is the ruling regarding divorcing the daughter and her father's wife taking her place.

Answer:

It is permissible for the first man to marry the wife of his wife's father, if she is not a mother to his wife. There is no sin upon him in marrying her, even if the daughter of her husband is with him, because there is no relation between the two wives, i.e., between his first wife and the wife of her father. What is forbidden is combining two sisters in marriage, or a woman and her maternal aunt, or a woman and her paternal aunt. Anything other than this is permissible according to the Words of Allah, Most High:

"All others are lawful, provided you seek (them in marriage) with Mahr (bridal-money given by the husband to his wife at the time of marriage) from your property."

and if it is permissible for a man to combine a woman and the wife of her father in marriage, then it is more fitting that he marry the wife of her father after parting from his wife.

As for the mother and her daughter, if the daughter is the wife, then her mother is permanently forbidden to him, simply due to the marriage contract, even if the mother is the wife and her husband has entered upon her (i.e., had sexual intercourse with her). This is because the daughter is permanently forbidden to him, and if he has not had sexual intercourse with her, she is forbidden to him until he parts from her mother, according to the Words of Allah, Most High:

"your wives" mothers, your stepdaughters under your guardian-ship, horn of your wives unto whom you have gone in"but there is no sin on you if you have not gone in unto them (to marry their daughters)

-up to His Words:
"and two sisters in wedlock at the same time, except for what has already passed."

and it has been authentically reported from the Prophet that he said:
"It is not permissible to combine (in marriage) a woman and her paternal aunt, nor between a woman and her maternal aunt "