Now we come to the taboos with regard to marriage, which reflect the sound nature, righteous morals, and straight behavior. In view of the fact that the Islamic ruling is legislated in favor of the human being and honoring him. The first forbidden marriage is to marry the woman women your fathers married except for what has already been done, that is what has gone previously before the revelation of these verses. For it was accustomed that if a man died and he was married, the son could marry his father’s wife, however, when Islam came, it forbids this habit and considered the stepmother as a mother, it is not permissible for the son to marry her.
إِنَّهُ كَانَ فَاحِشَةً وَمَقْتًا{Indeed, it was an immorality and hateful [to Allah] : They even call it a hateful marriage, and the child who comes from this marriage is called hatful, so even the instinct disgusts this matter, because it is obscene, immoral, abhorrent and rejected.
In the following verses, Allah (swt) states what is forbidden to a person through lineage and what is forbidden through nursing: