Deuteronomy 17:6-8

American Standard Version

⁶ At the mouth of two witnesses, or three witnesses, shall he that is to die be put to death; at the mouth of one witness he shall not be put to death. ⁷ The hand of the witnesses shall be first upon him to put him to death, and afterward the hand of all the people. So thou shalt put away the evil from the midst of thee.

⁸ If there arise a matter too hard for thee in judgment, between blood and blood, between plea and plea, and between stroke and stroke, being matters of controversy within thy gates; then shalt thou arise, and get thee up unto the place which Jehovah thy God shall choose;