Musnad Abu Ya'la al-Mawsili 159:1

Zuhayr ibn Harb narrated to us, Sufyan ibn 'Uyaynah narrated to us, from al-Zuhri, from al-A'raj, from Abu Hurayrah, who says: "You claim that Abu Hurayrah narrates many hadiths from the Messenger of Allah (may Allah bless him and grant him peace), and Allah is the Promised One. I was a poor man serving the Messenger of Allah (may Allah bless him and grant him peace) for the filling of my stomach. The Emigrants (Muhajirun) were occupied by trading in the marketplaces, and the Helpers (Ansar) were occupied by tending to their wealth. The Messenger of Allah (may Allah bless him and grant him peace) said: 'Whoever spreads his garment, he will not forget anything he hears from me.' So I spread my garment until he finished his speech, then I gathered it to myself, and I did not forget anything I heard from him."