And those prohibited by reasons [of legal cause] are: the women who breastfed [one], sisters through breastfeeding, mothers of one's wives, daughters of the wives with whom one has consummated the marriage, wives of one's sons, the father's wives, and combining [in marriage] between two sisters.

In sum, those explicitly mentioned in the Book [the Qur'an] as being forbidden are fourteen: seven by lineage, two by breastfeeding, four by affinity, and one by way of combination. As for those by lineage, the first of them are mothers. They are everyone whom you are linked to by birth, whether the name "mother" applies to her in reality—meaning the one who gave birth to you—or metaphorically, meaning the one who gave birth to the one who gave birth to you, even if they ascend. This includes your two grandmothers, the mother of your mother and the mother of your father, the two grandmothers of your mother, the two grandmothers of your father, and the grandmothers of your grandmothers and the grandmothers of your grandfathers, however high they ascend, whether they are heirs or not; all of them are mothers who are forbidden. Abu Hurayra mentioned Hajar, the mother of Ishmael, saying: "That is your mother, O Children of the Water of the Sky." And in the supplication: "O Allah, bless our father Adam and our mother Hawwa' (Eve)." As for daughters, they are every female linked to you by your birth, such as the daughter of one's own loins, daughters of sons, and daughters however low their generation descends, whether they are heirs or not; all of them are daughters who are forbidden, due to His saying, the Exalted: "...and your daughters." For every woman is a daughter of Adam, just as every man is a son of Adam. Allah the Exalted said: "O Children of Adam." As for sisters, they include those from all three aspects: from both parents, or from the father, or from the mother, due to His saying, the Exalted: "...and your sisters." There is no sub-classification for them. As for paternal aunts, they are the sisters of the father from the three aspects, and the sisters of the grandparents from the side of...