Is a father's statement to his daughter, "Your mother is unlawful to me like my mother if you enter my house after returning to your husband," considered to be ẓihār? And what are the legal implications of such a statement?

A father's statement to his wife, "You are unlawful to me, like my mother," if his daughter enters his house, is considered an explicit, conditional ẓihār. The majority of scholars hold that ẓihār takes effect upon the fulfillment of the condition, which is the daughter's entry. At that point, the father must refrain from sexual intimacy with his wife until he performs the expiation for ẓihār mentioned in Sūrat Al-Mujādalah, which is freeing a slave before they touch each other.

The father does not have the right to prevent his daughter from returning to her husband if she is still married to him, or if he divorced her and her waiting period ended, and then she agrees to return to him with a new contract, based on the Almighty's saying: "And when you divorce women and they have fulfilled their term, do not prevent them from remarrying their [former] husbands if they agree among themselves on an acceptable basis."