Musannaf Ibn Abi Shayba 19:757

Abu Bakr narrated to us, he said: Hafs bin Ghiyath narrated to us, from Ibn Jurayj, who said: A man was brought to Ali, and two men testified against him that he had stolen. He [Ali] took him for something regarding the affairs of the people, and he threatened the false witnesses, saying: "I will not be brought a false witness except that I will do such and such to him." He said: Then he sought the two witnesses but did not find them, so he released him.