Deuteronomy 17:6

17:6 At the mouth of two witnesses, or three witnesses, shall he who is to die be put to death; at the mouth of one witness he shall not be put to death.
-World English Bible

Other Translation

17:6 At the mouth of two witnesses, or three witnesses, shall he that is worthy of death be put to death; [but] at the mouth of one witness he shall not be put to death.
-King James Version