Deuteronomy 14:28-29

At the end of every three years take a tenth part of all your increase for that year, and put it in store inside your walls: And the Levite, because he has no part or heritage in the land, and the man from a strange country, and the child who has no father, and the widow, who are living among you, will come and take food and have enough; and so the blessing of the Lord your God will be on you in everything you do.