What is the ruling regarding a man's statement to his wife: "If you leave through this door, you are as unlawful to me as my mother is unlawful to me," intending to frighten her?

A husband's statement to his wife, "If you leave through this door, you are forbidden to me just as my mother is forbidden," is considered a conditional ẓihār, because he mentioned forbiddance and used the present tense, which indicates both the present and the future. If the wife does not leave through the door, then there is nothing upon the husband. However, if she does leave, it is considered an explicit ẓihār, and the expiation for ẓihār becomes obligatory before he can enjoy her.