Leviticus 23:21-22

21And ye shall make proclamation on the selfsame day; there shall be an holy convocation unto you: ye shall do no servile work: it is a statute for ever in all your dwellings throughout your generations.

22And when ye reap the harvest of your land, thou shalt not wholly reap the corners of thy field, neither shalt thou gather the gleaning of thy harvest: thou shalt leave them for the poor, and for the stranger: I am the LORD your God.