Deuteronomy 21:5

3And 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;

4And 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:

5And 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:

6And 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:

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