Parashas Vayikra · Aliyah 5 · Passuk 13
Chabad.org — English translation + Rashi
Torah Temima points to Horayot 2a–5a / Toras Kohanim on the chatat of the congregation.
E-Daf / Tsurras Hadaf
PDF of the daf / source
English: And if the whole congregation of Israel errs, and the matter is hidden from the eyes of the assembly.
Communal chatat for a mistaken ruling — the Sanhedrin’s error followed by public action.
When the community acts on a hidden (mistaken) ruling of the court regarding a lav, a special communal bull chatat is brought. This is the “par he’elem davar shel tzibbur.”