Nehemiah 12:45
They performed the duty of their God, and the duty of the purification, and so did the singers and the gatekeepers, according to the commandment of David, and of Solomon his son.
1 Chronicles 25:1-26
Moreover, David and the captains of the army set apart for the service certain of the sons of Asaph, and of Heman, and of Jeduthun, who should prophesy with harps, with stringed instruments, and with cymbals: and the number of those who did the work according to their service was:
1 Chronicles 23:28
For 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 rooms, and in the purifying of all holy things, even the work of the service of God's house;
2 Chronicles 23:6
But let no one come into the house of the LORD, except the priests, and those who minister of the Levites. They shall come in, for they are holy, but all the people shall follow the LORD's instructions.