Deuteronomy 24:19-20

19When you are harvesting in your field and you overlook a sheaf, do not go back to get it. Leave it 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, do not go over the branches a second time. Leave what remains for the foreigner, the fatherless and the widow.