Midrasch zu Wajikra 5:18

1) (Vayikra 5:18) ("And he shall bring a ram without blemish, from the flock, by your valuation for a guilt-offering to the Cohein. And the Cohein shall make atonement for his unwitting sin, wherein he sinned unwittingly. For he did not know, and it will be forgiven him.") "And the Cohein shall make atonement, etc.": Whence is it derived that if there came before him a possibility of forbidden fats, and he did not know (that it came before him, or that it might possibly have come before him; and there came before him again) a possibility of forbidden fats and he did not know — and blood, and pigul in one span of forgetfulness — (Whence is it derived) that he is liable for each one? From "his unwitting sin." If it came before him (definitely), and he did not know, whence is it derived that he is liable for only one (guilt-offering)? From "wherein he sinned unwittingly." If there came before him a possibility of forbidden fats and he knew, (and, again,) a possibility of forbidden fats and he knew — Rebbi says: Whence is it derived that just as he brings a sin-offering for each one, so he brings a suspended guilt-offering for each one? From "for his unwitting sin."

2) R. Elazar b. R. Shimon and R. Shimon b. R. Yehudah said in the name of R. Shimon: He is liable for only one, it being written "for his unwitting sin wherein he sinned unwittingly." "For he did not know (of the 'possibility' having come before him)" — to exclude his being informed by others. I might think (that he is not liable) even though he does not deny (their words); it is, therefore, written "For he did not know, and it will be forgiven him" — but if he does know, it will not be forgiven him.

3) Let us see whom he (the high-priest) is most like. If he is most like the congregation, let us derive (his rules) from (those of) the congregation; and if he is most like the nassi, let us derive (his rules) from (those of) the nassi. The congregation brings a bullock (as a sin-offering) and it does not bring an asham talui (a "suspended" guilt-offering [see Vayikra 5:18]), and the high-priest brings a bullock, and he does not bring an asham talui. Just as the congregation brings (a sin-offering) upon error in ruling and deed-unwittingness, so, the high-priest should bring (a sin-offering) only where these obtain.