Leviticus 8:15

“And he slew it, etc.] Not Aaron, nor any of his sons, who as yet were not fully consecrated and installed into their office, but Moses, as follows: and Moses took the blood; which was received into a basin when the bullock was slain: and put [it] upon the horns of the altar round about with his finger; upon the four horns of the altar, which were at the four corners of it, and dipping his finger into the blood, he besmeared the horns with it, and drew it about with his finger here and there; and so is said to be done round about the altar, as these horns were: and purified the altar; or cleansed it; not from moral guilt and pollution, which it was incapable of, but from all ceremonial…”

“Moses as the mediator of the covenant of the Law Galatians 3:19; Hebrews 8:6 was called to perform the priestly functions, in consecrating those on whom henceforth those functions were to devolve, and in inaugurating the legal order of sacrifices. See Exodus 40:23 note. The sin-offering was now offered for the first time. The succession in which the sacrifices followed each other on this occasion, first the sin-offering, then the burnt-offering, and lastly the peace-offering, has its ground in the meaning of each sacrifice, and became the established custom in later ages. The worshipper passed through a spiritual process. He had transgressed the Law, and he needed the atonement signified by…”

“8:15 Normally, the high priest performed these priestly duties. However, it would not be proper for the priests to ordain themselves, so Moses, acting as God’s representative, instituted the priesthood.”

“he slew it: Lev 1:5, Lev 1:11, Lev 3:2, Lev 3:8; Exo 29:10, Exo 29:11 Moses: Lev 4:7, Lev 4:17, Lev 4:18, Lev 4:30; Exo 29:12, Exo 29:36, Exo 29:37; Eze 43:19-27; Heb 9:18-23 to make: Lev 6:30, Lev 16:20; Ch2 29:24; Eze 45:20; Dan 9:24; Rom 5:10; Co2 5:18-21; Eph 2:16; Col 1:21, Col 1:22; Heb 2:17; The beginning of this verse may be rendered, "And Moses slew it, and took the blood," etc. We find it expressly said in Exodus, that Moses slew the sacrifices. Exo 29:11; Yet, in general, the offerer seems to have killed his own sacrifice. Leviticus 8:16”