1 Chronicles 23:4-5, 28-32

Then David said, “From all the Levites, 24,000 will supervise the work at the Temple of the LORD. Another 6,000 will serve as officials and judges. Another 4,000 will work as gatekeepers, and 4,000 will praise the LORD with the musical instruments I have made.”

The work of the Levites was to assist the priests, the descendants of Aaron, as they served at the house of the LORD. They also took care of the courtyards and side rooms, helped perform the ceremonies of purification, and served in many other ways in the house of God. They were in charge of the sacred bread that was set out on the table, the choice flour for the grain offerings, the wafers made without yeast, the cakes cooked in olive oil, and the other mixed breads. They were also responsible to check all the weights and measures. And each morning and evening they stood before the LORD to sing songs of thanks and praise to him. They 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. And 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.