1 Chronicles 23:30-32

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.