Zevachim 35A

אף אני לא אמרתי אלא כשנתקבל בכלי. והוא גופיה מנא ידע? כהנים זריזין, ועבדין הייא ומשתפכין.

I too said that the blood should be sprinkled only when it was collected in a vessel. The Talmud asks: But he, R' Yehuda, himself, from where did he know if the blood was indeed collected? The Talmud answers: He relies on the fact that priests are vigilant, and perform their service properly and collect all of the blood. But they work swiftly, and the blood therefore spills from the cup.

והלא דם התמצית מעורב בו! רבי יהודה לטעמיה, דאמר: דם התמצית קרוי דם.

The Talmud asks: But isn’t blood of exudate, which is unfit to be sprinkled upon the altar, mixed with the blood of the soul on the floor? The Talmud answers: R' Yehuda conforms to his standard line of reasoning, as he says that blood of exudate is considered blood.

דתניא: דם התמצית ⁠– באזהרה. רבי יהודה אומר: בכרת.

This is as it is taught in a baraita: Blood of exudate is subject to a prohibition, and one who consumes it receives lashes. This is not as severe as consuming blood of the soul, the blood that spurts out of an animal as it is being slaughtered, for which one is liable to receive karet. R' Yehuda says: One who consumes blood of exudate is liable to receive karet, as this blood is treated as proper blood.

והאמר רבי אלעזר: מודה רבי יהודה לענין כפרה שאינו מכפר, שנאמר: ״כי הדם הוא הנפש״⁠ –

The Talmud challenges this answer: But doesn’t R' Elazar say that R' Yehuda concedes with regard to atonement that presenting blood of exudate does not effect atonement, as it is stated: “For the soul of the flesh is in the blood; and I have given it to you upon the altar to make atonement for your souls; for it is the blood that makes atonement by reason of the soul” (Leviticus 17:11).