Midrash su Deuteronomio 24:17

(Devarim 14:29) "and the stranger, and the orphan, and the widow that are in your gates": I might think (that they take poor-tithe) whether or not they are needy. And do not wonder about this, for it is written (Ibid. 24;17) "You shall not take as a pledge the garment of a widow" — whether rich or poor. It is, therefore, written (Vayikra 23:22) "To the poor man and to the stranger shall you leave them." Just as a poor man is needy, so, all (to take poor-tithe) must be needy.

(Devarim 24:17) "You shall not pervert the judgment of a stranger and an orphan": What is the intent of this? Is it not already written (Ibid. 16:19) "You shall not pervert judgment"? Its intent is to teach that one who perverts the judgment of a stranger transgresses two negative commandments.