Deuteronomy 24:19-22

When you reap your harvest in your field and forget a sheaf in the field, you shall not go back to get it; it shall be left for the alien, the orphan, and the widow, so that the LORD your God may bless you in all your undertakings. When you beat your olive trees, do not strip what is left; it shall be for the alien, the orphan, and the widow. When you gather the grapes of your vineyard, do not glean what is left; it shall be for the alien, the orphan, and the widow. Remember that you were a slave in the land of Egypt; therefore I am commanding you to do this.