Numbers 4:49

According to the commandment of the Lord, they were numbered by the hand of Moses,.... Aaron and the chief of the congregation of Israel assisting it:

everyone according to his service; called in Numbers 4:47 "the service of the ministry", or "service of service", which Jarchi interprets of that part of the service of the Levites, which lay in singing the song with cymbals and harps; which, he says, was a service to another service; though it seems to be better explained, by Chaskuni, of their taking down and setting up of the tabernacle, which was a service incumbent on all the Levites:

and according to his burden: called "the service of the burden", Numbers 4:47; which the last mentioned writer restrains to the ark, table, candlestick, and altars, which the Kohathites carried on their shoulders; but may be extended to what each of them bore and carried when journeying:

thus were they numbered of him, as the Lord commanded Moses; from thirty years old to fifty, as Jarchi observes; for that was the order given to Moses by the Lord, which he punctually attended to, as a faithful servant in the house of God.