דברי הימים א, פרק ט״ז, פסוק מ״א

The offering of sacrifices in the Tabernacle was accompanied by a carefully organized arrangement of music and song. To elevate the holy service and praise God, this responsibility was given to a highly select group of individuals. These musicians worked in close coordination either alongside the priests who offered the sacrifices [מלבי״ם, שטיינזלץ], or together with Asaph and his brothers [רלב״ג].

Standing with them were Heman, Jeduthun, and an elite group of men handpicked specifically for this mission [רש״י, מצודת ציון, שטיינזלץ]. These were prominent individuals whose identities were explicitly recorded because of their greatness. Their designated role was to stand before the Tabernacle and sing at the altar while the public sacrifices were being offered [רש״י, מצודת דוד, מצודת ציון].

A clear division of musical roles existed among this group. While the majority of the chosen singers praised God using only their voices, Heman and Jeduthun were masters of both vocal and instrumental music. They joined the vocal chorus and simultaneously accompanied the singing by playing instruments such as trumpets and cymbals [רלב״ג, מלבי״ם]. Alongside the musicians, the sons of Jeduthun were assigned a separate, dedicated duty, serving as the gatekeepers [רלב״ג, מלבי״ם].

The ultimate purpose of this entire organized gathering was to thank God, as it is fitting and proper to express gratitude for His constant, eternal kindness [מצודת דוד].