Deuteronomy 24:20-22

20When thou shakest thine olive-tree, thou shalt not go over the boughs again; it shall be for the stranger, for the fatherless, and for the widow. 21When thou gatherest the grapes of thy vineyard, thou shalt not glean it afterwards; it shall be for the stranger, for the fatherless, and for the widow. 22And thou shalt remember that thou wast a bondman in the land of Egypt; therefore I command thee to do this thing.