EXOD718 Indeed, the amount of money owned by a person in excess of his needs is a trust fund deposited by the Master of the Universe, Who appointed him to administer it, to take pity on the unfortunate and to extend favors to the needy. On [this verse], R. Moshe Alshech has commented: "This is comparable to a person who has deeded all his money to one of his sons. [The law presumes that] he only intended to appoint this son a trustee, since it is reasonable to assume that he would not cut off the rest without anything. Hence the share of each of the other sons is held to be a trust fund kept with him. So in our case. God made one person rich. Is it possible to assume that he has left the rest in penury? Are they not his sons as well? God, then, appointed the rich person a trustee to support the poor, and their share with him exceeds his own portion." This is what the verse (Ibid), "the poor that is with you," conveys: Whatever the poor really needs belongs to him. It is deposited with you on his behalf, therefore you must not withhold it from him.