Musannaf Ibn Abi Shayba 2:62

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from ‘Awn ibn Abi Juhayfah, from his father, who said: I came to the Prophet, may Allah bless him and grant him peace, at al-Abtah. Bilal came out and gave the adhan. He said: It is as if I am looking at him, following his mouth here and here—meaning to the right and to the left.