Nehemiah 12:45
And they kept the charge of their God, and the charge of the purification, and'so did the singers and the porters, according to the commandment of David, and of Solomon his son.
1 Chronicles 25:1-26
Moreover David and the captains of the host set apart for the service certain of the sons of Asaph, and of Heman, and of Jeduthun, who should prophesy with harps, with psalteries, and with cymbals: and the number of them that 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 Jehovah, in the courts, and in the chambers, and in the purifying of all holy things, even the work of the service of the house of God;
2 Chronicles 23:6
But let none come into the house of Jehovah, save the priests, and they that minister of the Levites; they shall come in, for they are holy: but all the people shall keep the charge of Jehovah.