Musnad Abu Ya'la al-Mawsili 115:167

Abu Musa narrated to us, Mu'adh ibn Hisham narrated to us, my father narrated to me, from Qatadah, from Anas, who said: I was giving drink to Abu Talhah, Abu Dujanah, and Suhayl ibn Bayda' from a water skin of theirs that contained a mixture of unripe dates and ripe dates. Then someone entered upon us and said: "A matter has occurred today." We said: "And what is it?" He said: "Alcohol has been prohibited." So we overturned them, and we used to consider it alcohol on that day.