Musnad Abu Ya'la al-Mawsili 65:7

Muhammad ibn Abi Bakr al-Muqaddami narrated to us, Abu 'Awanah narrated to us, from 'Abd al-Malik—meaning ibn 'Umayr—from Jundub ibn Sufyan al-Bajali, who said: I heard the Messenger of Allah (may Allah bless him and grant him peace) say: "I am your forerunner at the Hawd (the Cistern)."