Deuteronomy 21:6

And all the elders of that city that are next unto the slain
man
The whole court of judicature belonging to it, all the magistracy of it; even though there were an hundred of them, Maimonides

shall wash their hands over the heifer that is beheaded in the valley:
in token of their innocence, and this they did not only for themselves, but for the whole city, being the representatives of it; see ( Psalms 26:6 ) ( Matthew 27:24 ) . Some think that this is a confirmation of the sense embraced by some, that it was a strong stream to which the heifer was brought; and there might be a stream of water here, and a valley also; though it would be no great difficulty to get from the city, which was near, a sufficient quantity of water to wash the hands of the elders with. This may denote the purification of sin by the blood of Christ, when it is confessed over him; and shows that priests and elders, ministers of the word, as well as others, stand in need of it; and that even those concerned in the death of Christ shared in the benefits of it.

F24 Hilchot Rotzeach, c. 9. sect. 3.