Are the wives of one's sons forbidden in marriage?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
The wives of one's sons (including sons of daughters, progeny descending from sons or daughters, near or far, related by kinship or fosterage) are forbidden immediately upon the contract. This applies because they are called 'Halilat' (wives) of the sons, based on "and the wives of your sons who are of your own loins" (Quran 4:23). There is no known scholarly disagreement on this point.