What is the Islamic legal ruling if a husband issues the third divorce to his wife on the first day of her menstrual period without knowing, and she informs him afterward?

Scholars have differed regarding the occurrence of divorce during menstruation. The majority hold that it occurs, while a group maintains that it does not occur. This latter view is the fatwa for many contemporary scholars, such as Sheikh Ibn Baz and Sheikh Ibn Uthaymeen, and the Permanent Committee, and it is the correct view. This is because it is contrary to Allah's law, as Allah's law is that a woman should be divorced when she is pure and not after intercourse. Furthermore, in the hadith of Ibn Umar, when he divorced his wife while she was menstruating, the Prophet (peace be upon him) ordered him to take her back and clarified that that was the waiting period for which Allah commanded women to be divorced. Therefore, divorce during menstruation does not occur, and the woman remains under her husband's conjugal bond.