2 Chronicles 5:12
Also 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:)
The verse belongs to the splendid dedication service held in the seventh month at the feast of tabernacles, when a great congregation from every part of the kingdom, with richly dressed representatives of many foreign nations, assembled before the temple. The ark was brought in with singing and music and with great ceremony, sacrifice being offered every six paces in following David's example. The sacred ark contained the two tables of stone bearing the Decalogue written by the finger of God, and it was set in its place in the oracle of the house, the most holy place, after which the priests came out of the inner sanctuary.
The wilderness tabernacle with its holy furniture, including the ark of the testament, had been brought to the temple. Solomon stood facing the great altar of burnt offering while the priests who had carried in the sacred furniture came out of the holy place to take their assigned places in the court. The singers were Levites of Asaph, of Heman, and of Jeduthun, with their sons and their brethren, arrayed in white linen with cymbals and psalteries and harps, and they took their assigned positions at the east end of the altar together with one hundred and twenty priests sounding with trumpets. Standing in those positions, they joined as one in praising and thanking the Lord until the house was filled with a cloud of God's glory.