2 Chronicles 5:11-12

11And it came to pass when the priests were come out of the holy place (for all the priests that were present were hallowed without observing the courses;

12and the Levites the singers, all they of Asaph, of Heman, of Jeduthun, with their sons and their brethren, clad in byssus, with cymbals and lutes and harps, stood at the east end of the altar, and with them a hundred and twenty priests sounding with trumpets),