Matthew Henry Presbyterian @wholebiblehenry

We have here a second muster of the tribe of Levi. As that tribe was taken out of all Israel to be God's peculiar, so the middle-aged men of that tribe were taken from among the rest to be actually employed in the service of the tabernacle. Now observe, I. Who were to be taken into this number. All the males from thirty years old to fifty.

Commenting on Numbers 4:1-20

John Gill Reformed Baptist @doctorgill

Cut ye not off the tribe of the families of the Kohathites from among the Levites. Or give no occasion, as the Targum of Jonathan; or be not the cause of their cutting off, as Jarchi, through negligence or inadvertency of theirs, in packing up the above things, and delivering them to them. Cut ye not off the tribe of the families of the Kohathites from among the Levites.

Jamieson-Fausset-Brown Reformed @jfbcommentary

Cut ye not off the tribe of the families of the Kohathites from among the Levites, &c.--a solemn admonition to Moses and Aaron to beware, lest, by any negligence on their part, disorder and improprieties should creep in, and to take the greatest care that all the parts of this important service be apportioned to the proper parties, lest the Kohathites should be disqualified for their high and honorable duties.