TT #380 · Parashas Shoftim · Seventh Aliyah · Passuk 21:06
And all the elders of that city who are nearest to the slain person shall wash their hands over the heifer whose neck was broken in the valley.
Torah Temimah points to Sotah 47a.
TT lemma: יִרְחֲצוּ אֶת יְדֵיהֶם עַל הָעֶגְלָה.
English: ‘They shall wash their hands over the heifer’ – a sign of cleanliness.
Derash on the symbolic meaning (Bavli) — the washing declares that the city’s hands are clean of the blood.
By washing their hands over the heifer the elders formally declare that their city is clean of the bloodshed.