Pesachim 59B

״והעלה הכהן את העולה״⁠ — שהעלה כבר.

“And the priest should offer the burnt-offering” (Leviticus 14:20); this is interpreted as referring to the burnt-offering that has already been offered. From here it is derived that the metzora achieves atonement even if the standard order is reversed and the burnt-offering is brought before the sin-offering.

אמר ליה רב שמן בר אבא לרב פפא: לדידך, דאמרת מעלה ומלינה בראשו של מזבח, קיימין ועבדינן מילתא לכהנים דאתו בה לידי תקלה, דסברי דיומיה הוא ואתו לאקטורי! אמר ליה: כהנים זריזין הן.

Rav Shemen bar Abba said to Rav Pappa: According to your opinion, that you said he brings them up and leaves them overnight at the top of the altar, do we stand and perform an action for the priests by which they may come to a mishap. As they may think that these fats are from offerings brought on that day, and so they may burn them that day, although these fats must be left until the next day. He said to him: Priests are vigilant and may be relied upon to avoid that mistake and to warn their fellow priests to be careful as well.

אמר ליה רב אשי לרב כהנא, ואמרי לה רב הונא בריה דרב נתן לרב פפא: והא כמה דלא מתקטרי אמורין כהנים לא מצו אכלי בשר, דתניא: יכול יהו כהנים רשאין בחזה ושוק קודם הקטרת אמורין, תלמוד לומר: ״והקטיר הכהן את החלב המזבחה״, והדר: ״והיה החזה לאהרן ולבניו״.

Rav Ashi said to Rav Kahana, and some say it Rav Huna, son of Rav Natan, said to Rav Pappa: But, isn’t it the case that as long as the sacrificial parts of the sin-offering have not been burned on the altar, the priests may not eat the meat? As it was taught in a baraita with regard to peace-offerings: I might have thought that the priests would be permitted to eat the breast and thigh, which are designated for them from the peace-offering, prior to burning the sacrificial parts of the offering on the altar. Therefore, the verse states: “And the priest should burn the fat upon the altar, and the breast should be for Aaron and his sons” (Leviticus 7:31). From here it is derived that the priest is first obligated to burn the fat, and only then: “The breast should be for Aaron and his sons.