Nedarim 36A

מתיב רב שימי בר אבא: אם היה כהן, יזרוק עליו דם חטאתו ודם אשמו.

Rav Shimi bar Abba raised an objection from the Tosefta (2:7): If the one who vowed to prohibit another from benefiting from him was a priest, he may sprinkle the blood of his sin-offering and the blood of his guilt-offering on the other’s behalf. Apparently, the priest may perform all sacrificial rites for one prohibited from benefiting from him, even those that require knowledge of the one for whom the offering atones.

דם חטאתו של מצורע ודם אשמו של מצורע. דכתיב: ״זאת תהיה תורת המצרע״, בין גדול ובין קטן.

The Talmud answers. The reference is to blood of the sin-offering of a metzora and blood of the guilt-offering of a metzora. These are offerings brought by a metzora who is lacking atonement, in order to complete his purification process, as it is written: “This is the law of the metzora” (Leviticus 14:2). And the verse comes to teach that the halakhot of a metzora apply to both an adult and a minor. This offering, too, does not require the knowledge of the one for whom the offering atones.

תנן: הכהנים שפיגלו במקדש, מזידין ⁠— חייבין. הא שוגגין ⁠— פטורין, אלא שפיגולן פיגול.

The Talmud cites another proof to resolve the dilemma with regard to the nature of the agency of a priest. We learned in a Mishnah: In the case of priests who rendered an offering piggul in the Temple, i.e., they sacrificed an offering intending to consume it after its appointed time, if they did so intentionally, i.e., with full awareness of the period during which the offering may be consumed, they are obligated to pay. The Talmud infers: If they did so unwittingly, they are exempt from payment. However, in any event, when they rendered the offering piggul, it acquired the status of piggul and is disqualified.