Is the gift that a father exclusively designated for his three unmarried daughters, consisting of a house, while compensating his two sons for their share of his inheritance in another house, considered unlawful in Islamic Sharia, especially since this gift came as a precautionary measure from the father due to one of his sons' financial problems and his desire to secure housing for his daughters?

A father's gift of a house is legitimate if it fulfills the following conditions: that it is done while he is of sound health and legally competent to dispose of property, that it is a completed act whereby he relinquishes control of the house and enables his children to dispose of it, and that he treats all his children equally in the gift. However, if the gift is contingent upon his death, or if he was not legally competent to dispose of property, or if he did not treat his children equally, or if possession was not taken, then it is considered void. It is not permissible to divide an inheritance during the lifetime of the inheritor.