Chabad.org — English translation + Rashi
Torah Temimah points to Toras Kohanim (Sifra), Vayikra Dibbura DeChovah, on 4:13 (kol adat Yisrael — the Sanhedrin) (unit 1; single primary locus per emergency Core plan).
Sefaria — Sifra / Toras Kohanim, Vayikra Dibbura DeChovah
English: “And if the whole congregation of Israel” — might the verse speak of a communal assembly? I reason: “edah” is said here and “edah” is said elsewhere…
Identification of edah with Sanhedrin — “edah” here means the Great Sanhedrin, not a random communal gathering.
The subject of the communal chatas is the Sanhedrin, not an ordinary assembly of Israelites. By equating the two occurrences of “edah,” the Sifra establishes that only the formal judicial body of seventy-one can generate the erroneous hora’ah that triggers the bull of the congregation.