וַיִּקְרַ֥ב אַהֲרֹ֖ן אֶל־הַמִּזְבֵּ֑חַ וַיִּשְׁחַ֛ט אֶת־עֵ֥גֶל הַחַטָּ֖את אֲשֶׁר־לֽוֹ׃
So Aaron drew near unto the altar, and slew the calf of the sin-offering, which was for himself.
Read kabbalistic (mystical) interpretation of Leviticus 9:8: and classical mystical sources.