Leviticus 8:15

8:15 and he slaughtered it. ¹  Moses then took the blood and put it all around on the horns of the altar with his finger and decontaminated the altar, ²  and he poured out the rest of the blood at the base of the altar and so consecrated it to make atonement on it. ³ 

Leviticus 8:30

Anointing Aaron, his Sons, and their Garments

8:30 Then Moses took some of the anointing oil and some of the blood which was on the altar and sprinkled it on Aaron and his garments, and on his sons and his sons’ garments with him. So he consecrated Aaron, his garments, and his sons and his sons’ garments with him.

[8:15]  ¹ sn Contrary to some English versions (e.g., NAB, NASB, NIV, NLT), Aaron (not Moses) most likely slaughtered the bull, possibly with the help of his sons, although the verb is singular, not plural. Moses then performed the ritual procedures that involved direct contact with the altar. Compare the pattern in Lev 1:5-9, where the offerer does the slaughtering and the priests perform the procedures that involve direct contact with the altar. In Lev 8 Moses is functioning as the priest in order to consecrate the priesthood. The explicit reintroduction of the name of Moses as the subject of the next verb seems to reinforce this understanding of the passage (cf. also vv. 19 and 23 below).

[8:15]  ² tn The verb is the Piel of חָטָא (khata’, “to sin”) and means “to de-sin” the altar. This verse is important for confirming the main purpose of the sin offering, which was to decontaminate the tabernacle and its furniture from any impurities. See the note on Lev 4:3.

[8:15]  ³ tn Similar to v. 10 above, “and consecrated it” refers to the effect of the blood manipulation earlier in the verse. The goal here was to consecrate the altar in order that it might become a place on which it would be appropriate “to make atonement” before the Lord.