Can a man marry the sister of his son’s wife?

It is haraam for a man to
marry the wife of his son as soon as the son does the marriage contract with
her, because Allaah says (interpretation of the meaning):

“Forbidden to you (for
marriage) are: … the wives of your sons who (spring) from your own loins”

[al-Nisa’ 4:23]. 

He may marry the mother of
his son’s wife, or her sister or her daughter – from a husband other than
his son – because Allaah says, after mentioning the women who are forbidden
for marriage, (interpretation of the meaning):

“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, desiring
chastity, not committing illegal sexual intercourse”

[al-Nisa’ 4:24]. 

So there is nothing in
sharee’ah to prevent the father marrying the sister of his son’s wife. 

And Allaah knows best.