whom We have made lawful for you. These are those mentioned in the words of the Most High:

“Forbidden to you in marriage are your mothers, your daughters, your sisters, your paternal aunts, your maternal aunts, your brothers’ daughters, and your sisters’ daughters.”

“Mothers” includes one’s paternal and maternal grandmothers, however far up the line, with no disagreement among the scholars that I know of. Likewise, “daughters” includes one’s son’s daughter and one’s daughter’s son’s daughter, however far down the line, with no disagreement that I know of. “Sisters” likewise includes full sisters and half-sisters through either parent. “Paternal aunts” and “maternal aunts” include the paternal and maternal aunts of both parents. “Brothers’ and sisters’ daughters” includes the female descendants of one’s siblings, however far down the line.

Thus, if his ascendants, his descendants, and the descendants of his more distant ascendants are forbidden to him—excluding the daughters of his paternal uncles and aunts and his maternal uncles and aunts—then, concerning “women forbidden through marriage,” he says that all women related to him through marriage are lawful for him except four categories. This contrasts with blood relatives: all a person’s female blood relatives are forbidden to him except four categories, whereas female relatives on either spouse’s side are all lawful except four categories: the wives of fathers, the wives of sons, the mothers of wives, and their daughters.

Each spouse is therefore forbidden to marry the other’s ascendants and descendants. A man is forbidden to marry his wife’s mother, her maternal and paternal grandmothers, and so on, however far up the line. He is also forbidden to marry his wife’s daughter—his stepdaughter—and her daughter’s daughter, however far down the line. His stepson’s daughter is likewise forbidden to him, as expressly stated by the well-known imams, al-Shāfi‘ī, Ahmad, and others. I know of no disagreement concerning this. He is also forbidden to marry his father’s wife, however far up the line, or his son’s wife, however far down the line.

These “four categories” are the women forbidden through marriage in the Book of Allah; and each spouse