• The brother’s daughter, his son’s granddaughter, and his daughter’s granddaughter, by the verse: “and the daughters of your brother.”

• The paternal aunt and the maternal aunt, by the verse: “and your paternal aunts and your maternal aunts.”

• The woman against whom liʿān (mutual imprecation) has been pronounced is forever forbidden to the man who imprecated her. Al-Juzajani narrates from Sahl ibn Saʿd: “The Prophetic practice concerning those who perform liʿān is that they are separated and never reunited.” Al-Muwaffaq said, “We are unaware of anyone who held a contrary view.”

Whatever is forbidden by lineage is likewise forbidden by breastfeeding. Every woman made unlawful through blood relations in the foregoing categories is equally unlawful through nursing—mothers, sisters, and so forth—by the verse: “Your mothers who nursed you and your nursing sisters,” and by the Prophet’s statement ﷺ, “Breastfeeding renders unlawful whatever blood relations render unlawful” (agreed upon).

By mere contract, a man is forbidden to marry his father’s wife and his grandfather’s wife, as in the verse: “Do not marry those women whom your fathers married.”