Musannaf Ibn Abi Shayba 13:1816

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from al-Hasan ibn Furat, from his father, Furat, who said: I had fifty dirhams owed to me by a man, so I went to demand payment from him while a man was listening. I stood with him before Shurayh, and he denied [the debt] to me. Shurayh said: "Your evidence." I said: "A man who was listening, and he is an acknowledger [of the debt] to me." He said: "Call him." So I called him, and he testified. He [Shurayh] said: "Stand up and give him his right."