1 Chronicles 24:20 -

The rest of the sons of Levi designated here are explained sufficiently clearly by 1 Chronicles 24:30 . They were those who were not of the sons of Aaron, not priests, but whose "office was to wait on the sons of Aaron for the service of the house of the Lord" ( 1 Chronicles 23:28 ), for certain specified work, some of which was of the more menial character. These, of course, do not exhaust the whole of the non-priestly Levites; for we read distinctly in the following two chapters of other detachments of the non-priestly Levites, whose office was as singers, doorkeepers, and treasure-keepers. And this consideration may of itself possibly be a sufficient account of the absence of any of the family of Gershonites in the list of the present chapter, though they do appear to view for other work in 1 Chronicles 26:21 , etc. Amram… Shubael. The latter of these two names marks the line of Moses, in his eider son, Gershon, whose son was Shebuel ( 1 Chronicles 23:15 , 1 Chronicles 23:16 ), as the former is the name of the father of Moses, and eldest son of Kohath.