David Organizes the Levites 

In addition to his preparations for the building of the temple, David also organizes the temple duties and personnel. This chapter introduces that organization. It deals primarily with those Levites who were to assist the priests in "the work of the service of the house of God" (verses 24, 28, 32), and gives a brief description of the work they were to do. It also points out specifically that the descendants of Moses were not given any special job beyond that of their fellow Kohathites (verses 14-17).

Note in verse 27 that David makes a change in how the Levites are to be numbered. Previously the Levites were not counted for service until age 30, apparently because the work of breaking down, transporting and setting up the tabernacle was considered too demanding and meticulous for younger men (verse 3; compare Numbers 4:2-3, Numbers 4:22-23, Numbers 4:29-30). At the end of his life, David points out that this constant moving of the tabernacle will no longer be necessary (1 Chronicles 23:25-26), and he allows the Levites to enter into the temple service at age 20, the age of "adulthood" for the rest of the tribes.