Numbers 4:34
And Moses and Aaron and the chief of the congregation numbered the sons of the Kohathites after their families, and after the house of their fathers,
Cross-reference
Numbers 4:2
Parallel
In Numbers 4:2, God commands the numbering of Kohathites — here Moses and Aaron execute that command.
1 Chronicles 23:24
Related theme
In 1 Chronicles 23:24, Levites are counted from age 20 for temple service — a later parallel to this numbering of Kohathites from 30-50.