1 Chronicles 23:3-6

All the Levites who were thirty years old or older were counted, and the total came to 38,000. Then David said, “From all the Levites, 24,000 will supervise the work at the Temple of the LORD. Another 6,000 will serve as officials and judges. Another 4,000 will work as gatekeepers, and 4,000 will praise the LORD with the musical instruments I have made.” Then David divided the Levites into divisions named after the clans descended from the three sons of Levi—Gershon, Kohath, and Merari.