Deuteronomy 21:6

3 and it shall be, that the city which is nearest to the slain man, even the elders of that city shall take a heifer of the herd, which hasn't been worked with, and which has not drawn in the yoke;

4 and the elders of that city shall bring down the heifer to a valley with running water, which is neither plowed nor sown, and shall break the heifer's neck there in the valley.

5 The priests the sons of Levi shall come near; for them the Lord your God has chosen to minister to him, and to bless in the name of the Lord; and according to their word shall every controversy and every stroke be.

6 All the elders of that city, who are nearest to the slain man, shall wash their hands over the heifer whose neck was broken in the valley;

7 and they shall answer and say, "Our hands have not shed this blood, neither have our eyes seen it.

8 Forgive, Lord, your people Israel, whom you have redeemed, and do not allow innocent blood in the midst of your people Israel." The blood shall be forgiven them.

9 So you shall put away the innocent blood from the midst of you, when you shall do that which is right in the eyes of the Lord.