And I have given the Levites as a gift to Aaron and his sons from among the people of Israel, to do the service for the people of Israel at the tent of meeting and to make atonement for the people of Israel, that there may be no plague among the people of Israel when the people of Israel come near the sanctuary.”
19. And I have given the Levites. He declares on what terms He desires to have them as His own, viz., that they may be directed by Aaron, and obey his commands; for by “a gift” is not to be understood such an act as that whereby a person resigns and cedes his own right to another; but, when He devotes them to the ministry...
We read before of the separating of the Levites from among the children of Israel when they were numbered, and the numbering of them by themselves (Num 3:6, Num 3:15), that they might be employed in the service of the tabernacle. Now here we have directions given for their solemn ordination (Num 8:6), and the performance of it, Num 8:20.
Commenting on Numbers 8:5-26
And Moses and Aaron, and all the congregation of the children of Israel,.... The several parties concerned in the consecration of the Levites: these did to the Levites according unto all that the Lord commanded Moses, so did the children of Israel unto them: which, as Jarchi notes, is said to the praise of them that did it, and of what was done by them...