Deuteronomy 24:18-22

but thou shalt remember that thou wast a bondman in Egypt, and the LORD thy God redeemed thee thence: therefore I command thee to do this thing. When thou cuttest down thine harvest in thy field, and hast forgot a sheaf in the field, thou shalt not go again to fetch it: it shall be for the stranger, for the fatherless, and for the widow: that the LORD thy God may bless thee in all the work of thine hands. When thou beatest thine olive tree, thou shalt not go over the boughs again: it shall be for the stranger, for the fatherless, and for the widow. When thou gatherest the grapes of thy vineyard, thou shalt not glean it afterward: it shall be for the stranger, for the fatherless, and for the widow. And thou shalt remember that thou wast a bondman in the land of Egypt: therefore I command thee to do this thing.