Charles Ellicott Commentary Leviticus 9:18-21

"He slew also the ox and the ram, the sacrifice of peace-offerings, which was for the people: and Aaron`s sons delivered unto him the blood, which he sprinkled upon the altar round about, and the fat of the ox and of the ram, the fat tail, and that which covereth [the inwards], and the kidneys, and the caul of the liver: and they put the fat upon the breasts, and he burnt the fat upon the altar: and the breasts and the right thigh Aaron waved for a wave-offering before Jehovah; as Moses commanded." — Leviticus 9:18-21 (ASV)

He slew also the bullock. —Better, and he slew, etc. With this peace offering, which was carried out according to the rules prescribed in Leviticus 3:1 and following, the sacrificial ceremony of the installation of the priesthood and the sanctification of the people concluded.