Does the milk of a man (milk of the stallion/Fahl) create prohibited relations?
Chapter on What is Prohibited to Marry and Combining Between Them and Other Matters
Al-Mughni
Book of Marriage
Primary text
If a child is suckled from milk resulting from a man's semen (i.e., a man has two wives, one suckles a girl and the other a boy), this creates prohibition just as lineage does, as the milk originates from the man. The child becomes the man's son, and the man becomes the child's father. The man's other children become the child's siblings (brothers and sisters), and the child's ascendants become the man's parents, making the man's siblings the child's paternal/maternal uncles and aunts. This view is held by the majority of scholars including 'Ali, Ibn 'Abbas, Malik, Al-Shafi'i, and Ahmad, supported by consensus among the jurists of Al-Hijaz, Al-'Iraq, and Al-Sham.
Supporting text
A dissenting opinion holds that fosterage is established only through the woman, not the man, and thus 'milk of the stallion' does not create prohibited relations. This view is attributed to Sa'id ibn al-Musayyab, Abu Salama ibn 'Abd al-Rahman, and others, supported by a narration involving 'Aisha (RA) regarding the request of Aflah, the brother of Abu Al-Qu'ays, to enter her presence after hijab was prescribed. However, the text concludes that the narration regarding 'Aisha is a decisive proof in favor of prohibition, and if the narration concerning Zaynab bint Abi Salama is authenticated, it also supports the view of non-prohibition.