For a sin — offering — That is, for the priest's sin — offering, called the first bullock, Leviticus 4:21.
Related Commentaries of Leviticus 4:20
Leviticus 4:20
20 And he shall do with the bullock as he did with the bullock for a sin offering, so shall he do with this: and the priest shall make an atonement for them, and it shall be forgiven them.