What is the legal status of divorce when a man divorces one of his wives but forgets or does not know which specific one it was?

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The ruling among most of our associates is that if a man divorces one of his wives and forgets which one, lot drawing (qur'ah) is used to determine the specific wife, and the divorce takes effect upon her, making the others permissible for him. However, Ismail bin Sa'eed narrated from Ahmad a view suggesting that lot drawing is not used here to establish permissibility (halal), but only for inheritance matters. Ahmad stated his dislike for ruling on divorce by lot drawing, but permitted it for inheritance, arguing that lot drawing pertains to property rights in the latter case. The general scholarly consensus is that lot drawing should not be used to determine who is permitted (for remarriage or resumption of relations) in cases of forgotten divorce.