1 Chronicles 23:24-27

24These were Levi’s descendants, who were grouped according to their families. The heads of their families were registered by name as they were counted. Everyone who served in the Lord’s temple was at least 20 years old.

25David had said, “The Lord God of Israel has given his people rest. He will now live in Jerusalem forever.

26The Levites will no longer have to carry the tent and all the utensils used in worship.”

27David’s last instructions were to count the Levites who were at least 20 years old.