Leviticus 23:20-22

And the priest shall wave them with the bread of the firstfruits as a wave offering before the LORD, with the two lambs. They shall be holy to the LORD for the priest. And you shall make a proclamation on the same day. You shall hold a holy convocation. You shall not do any ordinary work. It is a statute forever in all your dwelling places throughout your generations. “And when you reap the harvest of your land, you shall not reap your field right up to its edge, nor shall you gather the gleanings after your harvest. You shall leave them for the poor and for the sojourner: I am the LORD your God.”