Deuteronomy 21:6

3 And it shall be, [that] the city [which is] next unto the slain man, even the elders of that city shall take an heifer, which hath not been wrought with, [and] which hath not drawn in the yoke;

4 And the elders of that city shall bring down the heifer unto a rough valley, which is neither eared nor sown, and shall strike off the heifer’s neck there in the valley:

5 And the priests the sons of Levi shall come near; for them the LORD thy God hath chosen to minister unto him, and to bless in the name of the LORD; and by their word shall every controversy and every stroke be [tried]:

6 And all the elders of that city, [that are] next unto the slain [man], shall wash their hands over the heifer that is beheaded in the valley:

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

8 Be merciful, O LORD, unto thy people Israel, whom thou hast redeemed, and lay not innocent blood unto thy people of Israel’s charge. And the blood shall be forgiven them.

9 So shalt thou put away the [guilt of] innocent blood from among you, when thou shalt do [that which is] right in the sight of the LORD.