Is a person sinful if he prevents his father from taking his money and giving it to his brother, especially since they have their own income?

It is not permissible for a wealthy father to take his son's money without his consent; if he does so, he is an oppressive sinner. However, if the father is in need, he is permitted to take according to his need, and the son is obliged to give to him. What the father is doing by taking his son's money without his permission and giving it to his brother is impermissible. If the brother is not in need, the sin is greater, because he is prohibited from singling out some of his children for gifts from his own money, so prohibiting him from singling out his other son with money taken from the latter's son is even more paramount. There is no blame on the son if he prevents his father from taking this money, provided he appeases him in a kind manner.