Nehemiah 12:45
And both the singers and the gatekeepers kept the charge of their God, and the charge of the purification, according to the commandment of David, and of Solomon his son.
1 Chronicles 25:1-26
Moreover David and the captains of the army separated for the service some of the sons of Asaph, and of Heman, and of Jeduthun, who should prophesy with harps, with lyres, and with cymbals: and the number of the workmen according to their service was:
1 Chronicles 23:28
Because their office was to wait on the sons of Aaron for the service of the house of the LORD, in the courts, and in the chambers, and in the purifying of all holy things, and the work of the service of the house of God;
2 Chronicles 23:6
But let none come into the house of the LORD, except the priests, and they that minister of the Levites; they shall go in, for they are holy: but all the people shall keep the watch of the LORD.