וְכֹ֗ל זִקְנֵי֙ הָעִ֣יר הַהִ֔וא הַקְּרֹבִ֖ים אֶל־הֶחָלָ֑ל יִרְחֲצוּ֙ אֶת־יְדֵיהֶ֔ם עַל־הָעֶגְלָ֖ה הָעֲרוּפָ֥ה בַנָּֽחַל׃
And all the elders of that city, who are nearest unto the slain man, shall wash their hands over the heifer whose neck was broken in the valley.
Sifrei Devarim
(Devarim 21:6) "And all the elders of that city": Even if they are a hundred. Because we said above ([21:2] re the measuring), three or five, I might think that this is so here, too. (in respect to the washing of the hands); it is, therefore, written "and all the judges of that city" — even if they are a hundred.