The same applies to His statement: “Do not marry those women whom your fathers married.” It is well known that a foster-father is never included in the unqualified term “father”; he is called a father only when qualified as a foster-father.

As for His statement, “the wives of your sons,” it may serve as an argument against them, for Allah qualified the sons as being from one’s own loins, saying: “the wives of your sons who are from your own loins.” They reply that this qualification excludes an adopted son. It is then said: Allah would not need in the Quran to exclude a son who is not recognized by the Sacred Law, for such a son is not included in the first place and thus requires no qualification to exclude him. An adopted son is not legally a son at all.

Accordingly, the verse supports the view chosen by Shaykh al-Islam Ibn Taymiyyah, may Allah have mercy on him, which is the view we hold and regard as stronger: breastfeeding has no effect on marriage relations by affinity. This is because we have a general ruling in the Quran, which cannot be restricted except by clear evidence: “All beyond these are lawful for you.” The word “all” is a relative pronoun indicating generality. Thus, whenever someone says, “This woman is forbidden,” we say to him: Bring proof.

Accordingly, a man may marry his wife’s foster-mother, but only after he has separated from his wife through death or divorce; he may not be married to them both at the same time. This is due to the Prophet’s saying, peace and blessings be upon him: “Through breastfeeding, what is forbidden through lineage is also forbidden.” (1) Therefore, since marrying two sisters at once is forbidden through lineage, it is also forbidden through breastfeeding. Hence, Shaykh al-Islam, may Allah have mercy on him, was mistaken in this matter when he said that it is permissible to be married to two foster-sisters at once; and the fact that the majority of the Ummah