דברי הימים ב, פרק ל״א, פסוק ב׳

For a long period, the Temple service had ceased, leaving the sacred building in a state of desolation. The traditional divisions of the priests and Levites had faded into a mere theoretical memory. King Hezekiah takes decisive action to renew the holy service and restore the original order [ביאור שטיינזלץ]. He reestablishes the specific working groups of the priests and Levites who served in the Temple [מצודת דוד, ביאור שטיינזלץ]. This brings them back to the original framework established by King David, where each group served a rotating shift of seven days [רלב״ג]. Every individual is carefully placed into his exact and proper role [רש״י].

A clear division of labor is set between the two groups. The priests are specifically appointed to handle the burnt offerings and peace offerings, meaning their primary duty is to physically present the sacrifices upon the altar [מצודת דוד, מלבי״ם, ביאור שטיינזלץ].

In contrast, the work of the Levites is divided into several supporting roles. First, they provide physical assistance with various Temple duties, such as slaughtering the sacrifices and removing their hides [מלבי״ם]. Second, they are tasked with expressing thanks and praise through vocal singing and playing musical instruments [רש״י, מצודת דוד, מלבי״ם]. This musical worship is performed alongside the priests, who sound the trumpets [רלב״ג]. Finally, the Levites are stationed at the gates of the Temple [מצודת דוד, ביאור שטיינזלץ], where they serve as guards and gatekeepers at the entrances to the sacred compound [רש״י, רלב״ג, מלבי״ם].