a woman, she becomes his mother, and her husband, to whom the milk is attributed, becomes his father. Her children become his brothers and sisters. As for the nursed child’s biological siblings, father, and mother, they acquire no milk-kinship, and marriage to his milk-sisters is permissible for them—just as a man’s maternal half-sister may marry his paternal half-brother. All of this is agreed upon among the Muslims, without dispute. And Allah knows best.

He—may Allah have mercy on him—was asked:

“A married woman had milk that was not due to childbirth or pregnancy. She breastfed a girl under two years old on five separate occasions. This nursing woman is the girl’s paternal aunt by blood. Later, the nursing woman’s daughter’s son wished to marry the girl she had breastfed. Is this forbidden?”

He replied:

If her husband had intercourse with her and she subsequently began producing milk, breastfeeding with this milk establishes marriage prohibitions. Thus, if a girl nurses from her on five occasions, she becomes her daughter; the woman’s daughter’s son becomes the girl’s nephew, and she becomes his maternal aunt. This applies whether or not another child was also being nursed. As for the girl’s biological sister who was not breastfed, he may marry her.

Even supposing that such milk appeared in a woman who had never married, it establishes marriage prohibitions according to the schools of Abū Hanīfah, Mālik, and al-Shāfiʿī. This is also one position reported from Ahmad. The apparent position of his school, however, is that it does not establish marriage prohibitions. And Allah knows best.