1 Chronicles 23:27

Matthew Henry on 1 Chronicles 23:24–end

Here is, I. An alteration made in the computation of the effective men of the Levites - that whereas, in Moses's time, they were not enlisted, or taken into service, till they were thirty-years old, nor admitted as probationers till twenty-five (Num 8:24), David ordered, by direction from God, that they should be numbered for the service of the house of the Lord, from the age of twenty years and upwards, Ch1 23:24. This order he confirmed by his last words, Ch1 23:27. When he put his last hand to the draught of this establishment he expressly appointed this to be done for ever after; yet not he; but the Lord. 1. Perhaps the young Levites, having no work appointed them till twenty-five years…

Jamieson-Fausset-Brown on 1 Chronicles 23:24

OFFICE OF THE LEVITES. (Ch1 23:24-32) These were the sons of Levi . . . that did the work . . . from the age of twenty years and upward--The enumeration of the Levites was made by David (Ch1 23:3) on the same rule as that followed by Moses (Num 4:3), namely, from thirty years. But he saw afterwards that this rule might be beneficially relaxed, and that the enrolment of Levites for their proper duties might be made from twenty years of age. The ark and tabernacle being now stationary at Jerusalem, the labor of the Levites was greatly diminished, as they were no longer obliged to transport its heavy furniture from place to place. The number of thirty-eight thousand Levites, exclusive of pries…

Adam Clarke on 1 Chronicles 23:24

Twenty years and upward - It appears that this was a different ordinance from that mentioned Ch1 23:3. At first he appointed the Levites to serve from thirty years and upward; now from twenty years. These were David's last orders; see Ch1 23:27. They should begin at an earlier age, and continue later. This was not a very painful task; the ark being now fixed, and the Levites very numerous, there could be no drudgery.

John Gill