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 had sanctified themselves, and did not keep their courses;

12also the Levites which were the singers, all of them, even Asaph, Heman, Jeduthun, and their sons and their brethren, arrayed in fine linen, with cymbals and psalteries and harps, stood at the east end of the altar, and with them an hundred and twenty priests sounding with trumpets:)