The selection of the tribe of Levi for their unique role in the Tabernacle marks a profound spiritual and practical turning point, as the sacred duties transfer from the firstborns to the Levites. This privilege falls to them because they were the only tribe to remain pure and avoid the sin of idolatry during the incident of the Golden Calf [ברכת אשר]. The instruction to bring them near is not merely a technical physical movement, but an expression of spiritual elevation, drawing the Levites to a higher level of serving God [שד״ל, מלבי״ם].
They are appointed to a role of direct assistance and service by standing before Aaron the Priest [חזקוני, רש״ר הירש]. Placing them specifically before Aaron stems primarily from his position as the leader of the tribe of Levi [אבן עזרא]. Beyond this practical hierarchy, their placement sends a powerful public message to all the Israelites. By assigning the one pure tribe that did not participate in the Golden Calf to serve Aaron, God provides absolute proof that He has forgiven Aaron for his involvement in that very sin [שפתי כהן].
Regarding the nature of their duties, the primary approach among commentators is that their service is not an independent set of tasks, but rather the crucial work of guarding the Tabernacle. The heavy responsibility of protecting the sanctuary and ensuring that unauthorized individuals do not approach rests entirely on Aaron and the priests. The Levites are assigned to help shoulder this massive burden, freeing the priests from labor they would otherwise have to perform themselves [ספורנו, רש״ר הירש]. This protection is not purely functional; having guards and gatekeepers adds immense honor and majesty to the Tabernacle, much like the great estates of royalty [רלב״ג]. In fact, assisting the High Priest in this manner is considered entirely equivalent to serving God Himself [ברכת אשר].
The nature of this assistance is highly specific. The Levites are instructed to serve alongside Aaron, rather than serving him directly as personal subjects. This distinction ensures that they are not meant to perform his private chores, but to assist him strictly with the sacred service of the sanctuary [משכיל לדוד]. Despite their elevated status, their role remains firmly defined and limited. They do not perform the actual sacrificial rites; instead, they carry the Tabernacle, guard it, and sing during the services [בכור שור, מלבי״ם]. However, during pressing times when there is a shortage of priests, they are permitted to help with actions that are generally allowed for non-priests, such as the initial slaughtering of the sacrifices [בכור שור].
Though they are tens of thousands of individuals, the twenty-two thousand Levites need not wonder how such a massive crowd could possibly serve one man. They are viewed and treated as one unified body, operating much like a grand army serving a single king. This magnificent spectacle of an entire tribe serving the High Priest serves a vital public purpose: it visibly confirms God's choice of Aaron, effectively preventing the Israelites from ever challenging the legitimacy of the priesthood in the future [שפתי כהן].