a man who contracts an invalid marriage with a woman, divorces her, and then supposes that the divorce did not take effect, owing to his own error or that of the person who gave him a fatwa. He subsequently has intercourse with her, and she bears him a child. In this case, paternity is attributed to him, and she is regarded as a woman with whom marriage has been consummated. She therefore becomes forbidden in marriage, even if she has a mother with whom he has not consummated marriage, by scholarly consensus.

Thus, if a disbeliever marries a woman in a marriage he considers valid according to his religion, and his son subsequently accepts Islam—as happened among the Arabs whose children accepted Islam, and as frequently happens today—he may not marry his son’s wife, even if her marriage was invalid, by scholarly consensus. Paternity is established on the basis of the belief that intercourse was lawful, even if that belief was mistaken. Affinity follows paternity; when paternity is established, affinity is established all the more readily.

Likewise, “the child’s free status” depends on his father’s belief. A child follows his father in “lineage and free status,” and follows his mother in this, by scholarly consensus. In religion, the child follows whichever parent has the better religion, according to the overwhelming majority of scholars. This is the position of Abū Hanīfa, al-Shāfi‘ī, and Ahmad, and one of the two positions in Mālik’s school.

If a man has intercourse with another person’s slave woman, whether through marriage or fornication, his child is a slave belonging to her master. But if he purchases her from someone he believes to be her owner, or marries her believing her to be free, he is called “the deceived man.” Her child is free by agreement of the imams, because he believed he was having intercourse with a woman whose child by him would be free. Paternity and free status thus depend on the belief of the man having intercourse, even if he is mistaken; the same applies to marriage prohibitions arising from affinity.

The scholars differed only concerning outright fornication: does it establish marriage prohibitions through affinity? This is a well-known disagreement among earlier and later scholars. Abū Hanīfa and Ahmad hold that it does establish these prohibitions, whereas al-Shāfi‘ī holds that it does not. Two positions are reported from Mālik.