Musannaf Ibn Abi Shayba 3:1729

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Ash’ath ibn Abi al-Sha’tha’, who said: It was said to al-Aswad ibn Hilal, "Step forward [to lead the prayer]." He said, "Are you satisfied [with me]?"