Is it permissible for a mother, Islamically, to gift a portion of her property to her dutiful son, to the exclusion of his siblings who denied and ostracized her?

If a mother wishes to bequeath a portion of her property to her son as a will to be executed after her death, this is a bequest to an heir, which is Islamically prohibited unless the other heirs agree to it after her death. However, if it is an immediate gift, the fundamental principle is the obligation to be just among children in gifting, and it is not permissible to prefer some over others except for a legitimate Islamic reason, such as need, disability, or the transgression of one of the children. It must be noted that the reward for honoring parents is with Allah, and the intention should not be to obtain worldly possessions.