Musannaf Ibn Abi Shayba 13:3063

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Al-A’mash narrated to us, from ‘Umarah ibn ‘Umayr, who said: Two men testified before Shurayh for a man regarding something—Al-A’mash said: I think he said: regarding a mule. He said: Do you testify that this one bought this from this one? One of the witnesses said: I testify that he is a wicked person (fajir). Shurayh said: And what makes you know that he is a wicked person? Stand up, there is no testimony for you.