1 Chronicles 23:27-32

27For according to the final instructions of David, the Levites twenty years of age or older were counted, 28but their duty was to assist the descendants of Aaron with the service of the house of the LORD, being responsible for the courts and chambers, the purification of all the holy things, and the work of the service of the house of God, 29as well as for the rows of the showbread, the fine flour for the grain offering, the wafers of unleavened bread, the baking, the mixing, and all measurements of quantity and size.

30They were also to stand every morning to give thanks and praise to the LORD, and likewise in the evening. 31Whenever burnt offerings were presented to the LORD on the Sabbaths, New Moons, and appointed feasts, they were to serve regularly before the LORD in the numbers prescribed for them. 32So the Levites were to carry out the responsibilities for the Tent of Meeting and the Holy Place, and, under their brothers the descendants of Aaron, the service of the house of the LORD.