Deuteronomy 14:28-29

At the end of every third year, everyone should bring one-tenth of that year’s crop and store it in your towns. This is for the Levites so they may eat and be full. (They have no land of their own among you.) It is also for strangers, orphans, and widows who live in your towns so that all of them may eat and be full. Then the LORD your God will bless you and all the work you do.