TSK · 1 Chronicles 16:6

"The sons of Aaron, the priests, shall blow the trumpets. This shall be to you for a statute forever throughout your generations.

also the Levites who were the singers, all of them, even Asaph, Heman, Jeduthun, and their sons and their brothers, arrayed in fine linen, with cymbals and stringed instruments and harps, stood at the east end of the altar, and with them one hundred twenty priests sounding with trumpets;)

The Levites stood with the instruments of David, and the priests with the trumpets.