Deuteronomy 24:18-22

18Remember that you were slaves in Egypt, and the LORD your God redeemed you from that place. Therefore I am commanding you to do this.

19If you are harvesting in your field and forget a sheaf there, do not go back to get it. It is to be left for the foreigner, the fatherless, and the widow, so that the LORD your God may bless you in all the work of your hands.

20When you beat the olives from your trees, you must not go over the branches again. What remains will be for the foreigner, the fatherless, and the widow.

21When you gather the grapes of your vineyard, you must not go over the vines again. What remains will be for the foreigner, the fatherless, and the widow. 22Remember that you were slaves in the land of Egypt. Therefore I am commanding you to do this.