Deuteronomy 24:20-22

When you beat your olive trees, you shall not go over them again. It shall be for the sojourner, the fatherless, and the widow. When you gather the grapes of your vineyard, you shall not strip it afterward. It shall be for the sojourner, the fatherless, and the widow. You shall remember that you were a slave in the land of Egypt; therefore I command you to do this.