Numbers 8:12 (BSB)

And the Levites are to lay their hands on the heads of the bulls, and offer to the LORD one as a sin offering and the other as a burnt offering, to make atonement for the Levites.

From Numbers 8. Also in the ESV.

Commentary on Numbers 8:12

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Numbers 8:5-26: We read before of the separating of the Levites from among the children of Israel when they were numbered, and the numbering of them by themselves (Num 3:6, Num 3:15), that they might be employed in the service of the tabernacle. Now here we have directions given for their solemn ordination (Num 8:6), and the performance of it, Num 8:20.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Numbers 8:12: And the Levites shall lay their hands on the heads of the bullocks,.... Or "on the head" (s); on the head of everyone of them, as Aben Ezra, thereby, as it were, transferring their sins to them, for these were to make atonement for them, as the latter part of the verse shows; and this was a figure of the imputation of sin to Christ...
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on Numbers 8:12-19: Num 8:12-19 The Levites were then to close this transfer of themselves to the Lord with a sin-offering and burnt-offering, in which they laid their hands upon the sacrificial animals. By this imposition of hands they made the sacrificial animals their representatives, in which they presented their own bodies to the Lord as a living sacrifice well-pleasing to Him.