דברי הימים א, פרק ט״ז, פסוק ו׳

Establishing a permanent musical presence before the Ark of the Covenant required a careful and specific division of roles. The priests were entrusted with playing the trumpets, an instrument specifically designated for their use, and they maintained a constant and continuous sounding of these horns before the Ark [רש״י, ביאור שטיינזלץ].

Only two priests, Benaiah and Jahaziel, were appointed to this duty. This exact number aligns perfectly with the established law requiring two priests to sound the trumpets. Beyond playing the instruments, it appears these priests also joined in the vocal singing. Together with the rest of the participants, they formed a group of exactly twelve men. This reflects the rule that there must never be fewer than twelve singers standing on the platform. Since the primary purpose of this musical arrangement was for remembrance, a total of twelve men was considered sufficient for the occasion [מלבי״ם].