To signify that they offered it for themselves and for their own sins, which the offerer performing this rite was to confess, Leviticus 16:21, that they acknowledged themselves to deserve that death which was inflicted upon this innocent creature for their sakes, and to testify their faith in the future sacrifice of Christ, upon whom their sins were to be laid, and by whose blood they were expiated, and that they humbly begged God's mercy in pardoning their sins, and accepting them to and in their holy office.
Related Commentaries of Exodus 29:10
Exodus 29:10
10 And thou shalt cause a bullock to be brought before the tabernacle of the congregation: and Aaron and his sons shall put their hands upon the head of the bullock.