Verses 5-13:
"Bring the tribe of Levi near," not in a formal act of public presentation, but to assign to the Levites their appointed duties.
"Charge," mishmereth, "a thing to be watched." The Levites were to serve both Aaron and the congregation of Israel. The elaborate rituals of their religious duties required a large number of people to assist the priests. The Levites were to be trained and consecrated to this ministry.
"Instruments," keli, "vessels." This is an inclusive term, denoting armor, carriage, furniture, wares of various kinds.
The tribe of Levi was to be "wholly given" to Aaron by Jehovah God, not a personal possession but as ministers in the Tabernacle service, which was under the direction of Aaron and his descendants. But the Levites themselves were expressly forbidden to intrude into the priestly office, which was reserved exclusively for Aaron’s descendants.
Once again God affirms the law of the firstborn, see Ex 13:1, 2; 11-16; 34:19; Le 27:26-29. God claimed exclusive title to the firstborn. He assigned the unique distinction to the tribe of Levi to fill this role as the firstborn of Israel. This tribe was to be wholly dedicated to Him.