Musnad Abu Ya'la al-Mawsili 9:15

Zuhayr narrated to us, Abdullah ibn Numayr narrated to us, from Hajjaj, from Awn ibn Abi Juhayfah, from his father: That the Prophet, may Allah bless him and grant him peace, prayed facing an *Anazah* (a short spear/staff used as a sutrah).