Leviticus 9:2

For a sin-offering For himself and his own sins, which was an evidence of the imperfection of that priesthood, and of the necessity of a better. The Jewish writers suggest, that a calf was appointed to remind him of his sin in making the golden calf. Thereby he had rendered himself for ever unworthy of the honour of the priesthood; on which he had reason to reflect with sorrow and shame, in all the atonements he made.