Torah Temimah cites Toras Kohanim (Sifra, Vayikra Dibbura DeChovah, Section 10:1).
Sefaria — Toras Kohanim (Sifra, Vayikra Dibbura DeChovah, Section 10:1)
“And he shall confess” — from where that confession is required? Scripture says “and he shall confess.” And from where that his confession is while the animal is still alive? Confession is stated here and confession is stated there (Vayikra 16:21).
Gezeirah shavah of vidui — establishing both the requirement of confession and that it must be performed while the animal is still alive.
The oleh ve-yored requires verbal confession (vidui) over the live animal before it is slaughtered. The gezeirah shavah with the scapegoat’s confession on Yom Kippur locks the timing: confession is part of the living process of atonement, not a post-slaughter formality. Without this derivation, one might have thought that any verbal acknowledgment — even after the animal was dead — would suffice.