Is it permissible, in Islamic law, for a father to refuse to help his son, who is burdened with debts and needs money for the treatment of his sick child, given that the father is aware of his son's need and that his other children live comfortably?

A son is entitled to assistance from his father, especially if the father is well-off and the son is in dire need or has a debt he cannot repay. In such cases, it is permissible to give him a gift exclusively, without the other children. The father is not obligated to financially support his son if the son is able to earn a living, according to the majority of scholars. If the father is unable to provide financial support, scholars differ on whether it is obligatory for the grandfather to do so. The Maliki school does not consider it obligatory, while the Hanbali school deems it obligatory. It is not permissible to take a piece of the father's land in exchange for the son's share of the inheritance before the father's death.