2 Chronicles 29:24-26

ASV(i) 24 and the priests killed them, and they made a sin-offering with their blood upon the altar, to make atonement for all Israel; for the king commanded [that] the burnt-offering and the sin-offering [should be made] for all Israel.
25 And he set the Levites in the house of Jehovah with cymbals, with psalteries, and with harps, according to the commandment of David, and of Gad the king's seer, and Nathan the prophet; for the commandment was of Jehovah by his prophets. 26 And the Levites stood with the instruments of David, and the priests with the trumpets.