1 Chronicles 23:27-32

27For according to David’s final instructions, the Levites 20 years old and upward were counted.

28For their duty was to help the descendants of Aaron in the avodah of Adonai’s House concerning the courtyards and rooms, the purification of all holy things and the performance of the avodah of God’s House,

29the rows of bread, the fine flour for the grain offering, the matzot , the cake baked on the griddle or mixed and every measure of capacity and length,

30and to stand every morning to thank and praise Adonai. They also did this in the evening

31and whenever burnt offerings were offered to Adonai on Shabbatot, New Moons and the moadim. They were to serve regularly before Adonai, according to the proper number in the manner prescribed for them.

32They were to keep watch over the Tent of Meeting, the Holy Place and the sons of Aaron their kinsmen for avodah in the House of Adonai.