Numbers 18:23-24

23The Levites are to perform the work of the Tent of Meeting, and they must bear their iniquity. This is a permanent statute for the generations to come. The Levites will not receive an inheritance among the Israelites. 24For I have given to the Levites as their inheritance the tithe that the Israelites present to the LORD as a contribution. That is why I told them that they would not receive an inheritance among the Israelites.”