Is it forbidden for a man to marry his brother's daughter?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
It is forbidden for a man to marry his brother's daughter. This is the established ruling accepted by the majority of jurists, falling under the scope of relations prohibited by law.
Supporting text
Malik and the established opinion of Al-Shafi'i permit this marriage based on the view that she is legally an unrelated stranger (*ajnabiyyah*).