Does a husband's saying to his wife, "I am your father" or "I am your grandfather," during foreplay necessitate an expiation for ẓihār?

If the husband says to his wife, "You are like my mother" playfully and without intending ẓihār, then his ẓihār is not عقد (contracted) and no expiation is binding upon him. However, if he intends ẓihār, meaning that his wife becomes forbidden to him like the prohibition of his mother, then this is ẓihār and expiation becomes binding upon him if he has intercourse with her.