Zevachim 38B

מאי, לאו אפלגיה דמזבח ⁠– כדאמרי אינשי: ״טהר טיהרא דיומא״? אמר רבא בר שילא: לא, אגילוייה; דכתיב: ״וכעצם השמים לטהר״.

What, is it not referring to the middle of the side of the altar, as people say: Clear noon [tihara], that is the middle of the day? Accordingly, the root tet, heh, reish denotes the middle; in the one case, the middle of the day, and in the other case, halfway up the altar. Now, since the blood was sprinkled on the altar 7 times, inevitably some of the blood landed above the midpoint and some of it landed below the midpoint. Rava bar Sheila said: No, that is not the meaning of tohoro. Rather, tohoro means on the revealed part, i.e., the top, of the altar, as it is written: “Like the very clear [latohar] sky” (Exodus 24:10). Tohoro is referring to the top of the altar when it has been revealed, after the ashes of the incense are cleared and the pure gold is visible.

והאיכא שירים! שירים לא מעכבי.

The Talmud asks again: Is there not a case where some of the blood is presented above the red line and some of it is presented below? But there is the remainder of the blood, which is poured on the base of the altar even in the case of a sin offering, the main blood of which is placed on the upper portion of the altar. The Talmud answers: The pouring of the remainder of the blood on the base of the altar is not indispensable for atonement. Blood that is indispensable for atonement is in no instance presented half above the red line and half below it.