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 sanctified, and did not then wait by course:1 12Also the Levites which were the singers, all of them of Asaph, of Heman, of Jeduthun, with their sons and their brethren, being arrayed in white linen, having cymbals and psalteries and harps, stood at the east end of the altar, and with them an hundred and twenty priests sounding with trumpets:)