Charles Ellicott Commentary Exodus 29:10

"And thou shalt bring the bullock before the tent of meeting: and Aaron and his sons shall lay their hands upon the head of the bullock." — Exodus 29:10 (ASV)

Thou shalt cause a bullock to be brought. —Rather, the bullock: i.e., the bullock mentioned in Exodus 29:1, which was to be kept in readiness for the consecration sacrifice.

Aaron and his sons shall put their hands upon the head of the bullock. —By this symbolical action, which was commanded in the case of every sin offering (Leviticus 4:4; Leviticus 4:15; Leviticus 4:24; Leviticus 4:29; Leviticus 4:33; Leviticus 16:21, and elsewhere), the offerer identified himself with the animal and transferred to it the guilt of his own sins and imperfections.

The animal thereby became accursed, and its death paid the penalty due to the sins laid upon it, and set free those who had committed them. Similarly, Christ, our sin offering, was made a curse for us (Galatians 3:13).