—may Allah bless him and grant him peace—and the agreement of the imams. Neither man may therefore marry the other’s daughter, just as he may not marry his biological brother’s daughter, by agreement of the imams.

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

“A man has two female cousins, sisters who are daughters of his maternal aunt. One was breastfed with him, while the other was not. May he marry the one who was not breastfed with him?”

He replied:

If he received five breastfeedings from the same woman as she did within his first two years, he became the nursing woman’s son. All her daughters became forbidden to him in marriage, whether born before or after the breastfeeding, because they are his sisters, by agreement of the scholars. Whenever a prospective bride has been breastfed by a woman, she may not marry any of that woman’s sons. However, if the suitor was not breastfed by the prospective bride’s mother, and she was not breastfed by his mother, they may marry one another, by agreement of the scholars, even if her siblings shared breastfeeding. Allah knows best.

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

“A woman hired a wet nurse to breastfeed her daughter for a day or a month, and years have since passed. The wet nurse has a son born before the girl. Is it lawful for the two to marry?”