His statement, “The waiting period of a woman with whom intercourse took place under a mistaken assumption, through fornication, or under an invalid marriage contract is like that of a divorced woman,” is subject to the preceding details: it may be completed by delivery, by three menstrual periods, by three months, by one year, or by waiting until menstruation returns. The point is that the waiting period of a woman with whom intercourse took place under a mistaken assumption is the same as that of a divorced woman, because the man had intercourse with her believing her to be his wife. Thus, she is like a divorced woman on the basis of the intercourse partner’s belief. Mistaken assumption is of two types: one relating to the marriage contract and the other relating to one’s belief.

Mistake relating to the contract concerns the contract by which intercourse was deemed permissible, whereas mistake relating to belief concerns the supposition of the legally responsible person.

An example of a mistake relating to the contract is that a man marries a woman without knowing that she is his foster sister, and it then becomes clear that she is his sister. Another example is that he marries her without a guardian, thinking that the marriage is valid without one.

As for a mistake relating to belief, an example is where a man has intercourse with a woman whom he never married, but believes her to be his wife. There was no marriage contract in this case, for us to say that there was some ambiguity in the contract; rather, he erred in his supposition, believing her to be his wife and thus having intercourse with her. Her waiting period is therefore like that of a divorced woman—that is, she observes it in one of the ways mentioned above. This is the well-known position of the school.

The correct view, however, is that she does not observe the waiting period of a divorced woman; rather, it is sufficient for her to undergo one menstrual period to establish that her womb is free. This was the view chosen by Shaykh al-Islam Ibn Taymiyyah, may Allah have mercy on him. The reason the waiting period of a wife divorced by her husband is three menstrual periods is not merely to establish that the womb is free, but also to preserve the husband’s rights, by extending the period available to him should he wish to take her back. Does this apply in her case? No, because he is not her husband, such that his time might need to be extended in case he wishes to take her back. Rather, the purpose is only to establish that her womb is free, and this is achieved by one menstrual period. This is from the standpoint of legal reasoning. As for the textual evidence, Allah only made the waiting period obligatory upon