It is not permissible to designate one of the children for inheritance

Question: A girl inherited money from her father, and he designated her for the entire inheritance to the exclusion of her brother, and he made a bequest regarding that money. The father forbade the daughter from giving her brother any of this money after his death. However, what happened after the father’s death was that the sister felt compassion for her brother, so she appointed him as her agent over the entire inheritance along with the entire bequest, so that he could manage it, because he is weak and has dependents, and he has no money.
This son was involved in an accident, and it was said that he lost part of his mind, so the son denied that he had taken money from his sister. He neither returned the money nor carried out his father’s bequest. Is there any blame on me for disobeying my father’s bequest if I give (my brother) the entire inheritance to dispose of it, despite my father’s refusal of that? May Allah reward you with good.

Answer: It is not permissible for a Muslim to designate some of his heirs for something in excess of their right; because of the saying of the Prophet (peace and blessings be upon him): Therefore, it is obligatory to divide the estate between them according to the division of Allah. If there are other heirs with them, each is given his right. If there is a dispute in the matter, it is referred to the court. And success is from Allah.