LEV971 Do not wrong one another in buying and selling. It is common sense that deceit in business cannot be tolerated. One cannot take advantage of other people and extract from them what one does not deserve. Rather, each person profits according to his efforts, according to what Hashem grants him through justice and fairness. The benefit is universal. Just as one will not cheat others, so, too, they will not cheat him. Thereby, a great positive purpose is served that helps society to function smoothly.