Is the brother considered unjust if he asks his unemployed sister for a portion of her share of the money she inherited from the sale of a house, knowing that this money represents an inheritance for her and her sisters from him, and she will not forgive him if she gives him the money, and he is not entirely of sound mind, and she is in need of this money?

It is permissible for a brother to ask his sister for money in exchange for a service that is not obligatory for him, as long as the service has a wage, and there is no injustice in that. If the sister refuses to pay, she has the right to do so, and the brother is not entitled to force her. As for maintenance, it is not obligatory for the brother if the sister is self-sufficient. However, the more authoritative opinion is that a well-off brother must provide maintenance for his needy sister in a reasonable manner.