Deuteronomy 19:15-17

15One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established.

16If a false witness rise up against any man to testify against him that which is wrong;

17Then both the men, between whom the controversy is, shall stand before the LORD, before the priests and the judges, which shall be in those days;