Midrasz do Kapłańska 4:22

1) (Vayikra 4:22): "If (asher) a leader (nassi) sin ["asher," similar to "ashrei" ("fortunate")]: R. Yochanan b. Zakkai said: Fortunate is the generation whose nassi brings a sin-offering for his unwitting sin. If he brings a sin-offering for his unwitting sin, how much more so (is he contrite over) his deliberate sin. And if his nassi brings a sin-offering, how much more so is he (the common man) moved to bring a sin-offering (for his sin)! "a nassi": I might think the nassi of a tribe, like Nachshon; it is, therefore, written: "And he do one of all the mitzvoth of the L–rd his G d," and, elsewhere, (in respect to a king) (Devarim 17:19): "so that he may learn to fear the L–rd his G d." Just as there, the nassi is one who has no one above him but the L–rd his G d, so, here. (Scripture speaks of) a nassi who has no one over him but the L–rd his G d (i.e., a king).

2) — But why not say: Just as idolatry is characterized by being liable to judicial death penalty, so, all acts thus liable are included (in liability for a sin-offering)! And what will I include? One who curses his father and mother, an inciter (to idolatry), a necromancer, a false prophet, and scheming witnesses. — (These are not included for it is written (Vayikra 4:22): "And he do (… unwittingly"), to exclude those (transgressions) where there is no act.

2) Why "(If) a nassi shall sin" (instead of "sinned")? For otherwise I might think that he must bring (a he-goat) for (unwitting transgressions committed) prior to his appointment. But (why the exclusion clause?) Is it not a kal vachomer (that he should not bring a he-goat?), viz.: If the high-priest, who brings his sin-offering (a bullock) for (unwitting sins committed) after removal from office, does not bring (a bullock) for (unwitting sins committed) prior to his appointment — a nassi, who does not bring his sin-offering (a he-goat) for (sins committed) after removal from office, how much more so should he not bring it for (sins committed) prior to his appointment! — No, this may be so with the high-priest, who does not bring (his sin-offering, a bullock,) for deed-unwittingness (alone, but only as a result of ruling mistakenly for himself), as opposed to a nassi, who does bring (his sin-offering, a he-goat,) for deed-unwittingness (alone). And since he does, I would think that he brings (a he-goat, too,) for prior sins; it is, therefore, written (to negate this): ("If a nassi) shall sin," after he is appointed; but he does not bring it for those sins which he committed as a lay person.