Numbers 18:23

The 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.

But the Levites shall do the service of the tabernacle of the congregation, and they shall bear their iniquity: it shall be a statute for ever throughout your generations, that among the children of Israel they have no inheritance.