Charles Ellicott Commentary Numbers 3:7

"And they shall keep his charge, and the charge of the whole congregation before the tent of meeting, to do the service of the tabernacle." — Numbers 3:7 (ASV)

And they shall keep his charge. —The word rendered charge may mean the directions which the Levites should receive from Aaron ; or—as seems more probable from the use of the same word in this and the following verse with reference to the congregation—it may refer to the charge which was laid upon Aaron and upon the whole congregation in matters pertaining to the public worship of God.