Numbers 8:22 And after that went the Levites in to do their service in the tabernacle of the congregation before Aaron, and before his sons: as the LORD had commanded Moses concerning the Levites, so did they unto them.

Numbers 9:23 At the commandment of the LORD they rested in the tents, and at the commandment of the LORD they journeyed: they kept the charge of the LORD, at the commandment of the LORD by the hand of Moses.