1 Chronicles 23:3

Now the Levites were numbered from the age of thirty years, and upward,.... So they were numbered in the days of Moses, and by his order, and so they were now at first; though afterwards there was a new reckoning of them, 1 Chronicles 23:24

and their number by their posts; or, according to their heads:

man by man, was thirty and eight thousand; which vastly exceeds the number in the times of Moses; see Numbers 4:47, but then those above fifty years of age were not numbered, as they now might; since their work in the temple would be much more easy, no burdens to carry, as the ark, the vessels, c.