Bull of the Sin Offering. Following this, Moses clothed Aaron’s sons, after which he caused Aaron and his sons to lay their hands on the head of the bull of the sin offering, their action signifying their acknowledgment of the offering as being for them, the priestly house. After slaughtering the bull, Moses put some of the blood on the altar and poured the rest out at the base of the altar, thus symbolizing cleansing from the defilement brought because of the sinful nature of the priests who officiated at the altar. The blood being put on the horns of the altar evidently signified that the power of the sacrificial arrangement lay in the shed blood of the sacrifice. (Heb 9:22) The sprinkling of the altar was likewise required in connection with other offerings. (Le 1:5, 11; 3:2; 4:6; 16:18) Notice, however, that this being ‘ordination day’ for the priesthood and not the national atonement day for sins, the bull’s blood was not taken into the Most Holy. (See Le 16:14.) As with other sin offerings, the fat upon the intestines, the appendage of the liver, and the two kidneys with their fat were placed on the altar. (Le 4:8-10, 20, 26, 31) The rest of the bull, with its skin and dung, was taken outside the camp to be burned.​—Le 8:13-17.

The installation took seven days, before the end of which the priesthood could not officiate in the fullest sense. On each of the days, a bull was sacrificed as a sin offering to purify the altar.