Maintaining perfect order within the Tabernacle requires clear boundaries of responsibility. To prevent any overstepping of authority and to ensure the sacred service functions flawlessly, a precise division of labor is established between the Priests and the Levites.
The duties of the Levites are divided into two distinct categories. The primary approach among commentators is that their first responsibility involves assisting the Priests directly [רש ר הירש, ביאור יש״ר]. This includes practical tasks like preparing the needs for the sacrifices and appointing treasurers [רלב״ג, העמק דבר]. It also extends to guarding the Holy of Holies, ensuring that unauthorized individuals do not approach the sacred space [ספורנו, בכור שור]. The second category encompasses the independent duties of the Levites. These involve the physical management of the Tabernacle, such as setting it up, dismantling it, and carrying its parts during travel, as well as providing a constant external guard around the sanctuary day and night [ספורנו, רלב״ג, ביאור יש״ר, ביאור שטיינזלץ].
Despite their crucial role, the Levites are strictly restricted from specific areas of activity. They are forbidden from approaching the holy vessels located inside the sanctuary, such as the Menorah, the Table, and the Golden Altar [ספורנו, ביאור יש״ר], or the Ark of the Covenant [מלבי״ם]. A unique perspective suggests that these restricted objects also include specific musical instruments, warning the Levites not to use the special trumpets reserved exclusively for the Priests [צפנת פענח]. Additionally, the Levites are barred from the outer altar used for burnt offerings [ספורנו, ביאור יש״ר]. This restriction is not merely about physical proximity or touching the objects while transporting them [ביאור שטיינזלץ]. Rather, it serves as a strict warning against actually performing the sacred service that belongs to the Priests [העמק דבר, רש ר הירש].
The severity of violating these boundaries is underscored by a penalty of death, a consequence that applies equally to both the Priests and the Levites [אבן עזרא]. This shared consequence reveals a deep level of mutual responsibility. The Priests are held accountable for the actions of the Levites; if they allow the Levites to perform duties outside their designated roles, the Priests will share in their punishment and perish alongside them [בכור שור, רלב״ג].
Furthermore, the prohibition against swapping roles is entirely mutual. Just as the Levites are forbidden from performing the work of the Priests, the Priests are equally warned against taking on the duties of the Levites [רבנו בחיי, פענח רזא, רש ר הירש]. This strict adherence to assigned roles extends even within the tribe of Levi itself. A Levite appointed as a singer cannot serve as a gatekeeper, and one family cannot perform the work assigned to another [אור החיים, רלב״ג, תורה תמימה, רבנו בחיי].
Alongside these severe warnings, the parallel drawn between the two groups hints at a profound connection in their service. Just as the Priests have a dedicated, hands-on role at the altar, the Levites have an equally essential, parallel role deeply connected to that same altar: providing the sacred song that accompanies the sacrifices [תורה תמימה, מלבי״ם].