1 Chronicles 23:30-32

30And each morning and evening they stood before the Lord to sing songs of thanks and praise to him.

31They assisted with the burnt offerings that were presented to the Lord on Sabbath days, at new moon celebrations, and at all the appointed festivals. The required number of Levites served in the Lord’s presence at all times, following all the procedures they had been given.

32And so, under the supervision of the priests, the Levites watched over the Tabernacle and the Temple and faithfully carried out their duties of service at the house of the Lord.