and her milk-brother’s father, since no marriage prohibition exists between her and any of them. This differs from blood relationships: a woman may not marry her biological son’s brother, because he is her stepson, her husband’s son; nor her biological son’s grandfather, because he is her husband’s father; nor her maternal brother’s father, because he is her mother’s husband. A man may, however, marry his brother’s sister, whether the relationship is through blood or breastfeeding, since no marriage prohibition exists between them. Likewise, a man may marry his paternal uncle’s sister, whether the relationship is through breastfeeding or blood, since no marriage prohibition exists between them.

A paternal uncle through breastfeeding may be related to you in three ways. First, your biological father may have a milk-brother because the same woman nursed them both during their respective two-year nursing periods, or because two women nursed them with milk attributable to the same man. That brother is then your paternal uncle through breastfeeding. Second, your milk-father—the man whose wife or slave woman nursed you with milk attributable to him—may have a biological brother, who is then your paternal uncle through breastfeeding. Third, your milk-father—the man whose wife nursed you with milk attributable to him—may have a milk-brother because the same woman nursed them both, or because two women nursed them with milk attributable to the same man. That brother is then your paternal uncle through breastfeeding. All of this is clear, and praise belongs to Allah.

Section
On the Marriage Prohibition Established Through the Milk-Father

Scholars have differed concerning milk attributable to the father. One group held that it establishes a marriage prohibition just as the mother’s milk does. This is the position of Mālik and all his disciples, al-Shāfiʿī and Abū Hanīfa and their respective disciples, al-Thawrī, Ahmad ibn Hanbal, and most scholars. Another group disapproved of such marriages, including al-Qāsim ibn Muhammad, ʿUrwa ibn al-Zubayr, Mujāhid, and al-Shaʿbī. A further group permitted them: Saʿīd ibn al-Musayyab, Sulaymān ibn Yasār, ʿAtā’ ibn Yasār, and al-Nakhaʿī. The ruling followed in practice is that this milk establishes a marriage prohibition.

Their disagreement arose—and Allah knows best—because they regarded ʿĀ’isha’s acting contrary to the hadith she herself narrated on this matter as a flaw in that report. It is reported that she did not consider a marriage prohibition to arise through the milk-father. Thus, men nursed by her brother’s daughters or her sister’s daughters would enter her presence, whereas those nursed by her brothers’ wives would not. Yet she herself narrated from the Prophet ﷺ that milk attributable to the father establishes a marriage prohibition, and she accepted this ruling after raising the matter with the Prophet ﷺ, saying: “O Messenger of Allah, it was the woman who nursed me, not the man.”

The authoritative proof lies in the Sunnah, not in what contradicts it, even if the person acting contrary to it is its narrator. It has also been said that his acting contrary to it invalidates