Is it permissible for a father to sell a portion of his property to his daughters in exchange for them relinquishing their inheritance rights to their brothers, so that the property is divided among the male heirs only after his death? And if it is not permissible, then what is obligatory to do?

It is not permissible for a father to stipulate that his daughters relinquish their share of inheritance in exchange for him selling them his properties, whether the price is specified or their share of the inheritance. This is a corrupt condition that invalidates the sale, for the Prophet, peace and blessings be upon him, said: "Any condition that is not in the Book of Allah is null and void, even if there were a hundred such conditions." Furthermore, scheming to deprive daughters of inheritance contravenes Islamic law and the customs of the pre-Islamic era (Jahiliyyah). Even if they agree to relinquish their right during their father's lifetime, they are not bound by it after his death, because it is the waiver of a right before it becomes due. The father must fear Allah and dread His punishment, for the obligations of inheritance have been clearly outlined by Allah, and He has warned those who violate them.