Numbers 1:47-50

47But the Levites after the tribe of their fathers were not numbered among them.

48For Jehovah had spoken to Moses, saying,

49Only thou shalt not number the tribe of Levi, neither take the sum of them among the children of Israel.

50But thou, appoint the Levites over the tabernacle of testimony, and over all the vessels thereof, and over all things that belong to it: they shall bear the tabernacle, and all its vessels; and they shall serve it, and round about the tabernacle shall they encamp;