Deuteronomy 24:18-22

18but thou shalt remember that thou wast a bondman in Egypt, and Jehovah thy God redeemed thee thence: therefore I command thee to do this thing.

19When thou reapest thy 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 sojourner, for the fatherless, and for the widow; that Jehovah thy God may bless thee in all the work of thy hands. 20When thou beatest thine olive-tree, thou shalt not go over the boughs again: it shall be for the sojourner, for the fatherless, and for the widow. 21When thou gatherest the grapes of thy vineyard, thou shalt not glean it after thee: it shall be for the sojourner, 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.