Is it permissible for the husband's father to marry the wife's mother?

If the husband's father is a stranger to the wife's mother, and there is no prohibited degree of kinship between them, then it is permissible for him to marry her because she is not among those women who are forbidden. The Noble Verse states: "And lawful for you are [all others] beyond these, [provided] that you seek them with your wealth, as chaste spouses, not [unlawful] sexual partners." As stated in the fatwas of the Permanent Committee, "It is not permissible for the husband's father to see the mother of his son's wife, because she is not a mahram to him."