In Context

18 Cut ye not off the tribe of the families of the Kohathites from among the Levites:

19 but thus do unto them, that they may live, and not die, when they approach unto the most holy things: Aaron and his sons shall go in, and appoint them every one to his service and to his burden:

20 but they shall not go in to see the sanctuary even for a moment, lest they die.

21 And the LORD spake unto Moses, saying,

22 Take the sum of the sons of Gershon also, by their fathers' houses, by their families;

23 from thirty years old and upward until fifty years old shalt thou number them; all that enter in to wait upon the service, to do the work in the tent of meeting.

Numbers 4:21 in Other Translations