Does a wife become forbidden to her husband if he said to her: "If you leave the house and do not tell me the truth, and I find out from someone else, you are forbidden to me, just as my sister is forbidden to me," and then he left and she did not inform him?

A husband's statement to his wife, "You are forbidden to me just as my sister is forbidden to me," is considered ẓihār. If the husband made this ẓihār conditional on his wife not telling him the truth before he left, and he left without her informing him, then the ẓihār has occurred. However, if he made it conditional on her not informing him and on him learning the truth from someone else, then it does not occur unless both conditions are met. If the truth is not revealed to him from someone else, then ẓihār has not occurred.

In the event that ẓihār has occurred, its expiation (kaffārah) is obligatory before the husband touches his wife. This expiation is fasting for two consecutive months, or if unable, feeding sixty poor persons. Ibn Taymiyyah is of the view that the expiation for a conditional ẓihār is like the expiation for an oath (yamīn): feeding ten poor persons or clothing them, or fasting three days for one who cannot find that. It is imperative to avoid such forbidden expressions.