Musnad Abu Ya'la al-Mawsili 110:43

Ibrahim ibn al-Hajjaj narrated to us, Hayyan ibn Ubayd Allah ibn Hayyan Abu Zuhayr al-Adawi narrated to us, Abu Mijlaz narrated to us, from Ibn Abbas, who said: And Abdullah ibn Buraydah narrated to us, from his father, that the banner (rayah) of the Messenger of Allah, may Allah bless him and grant him peace, was black, and his standard (liwa') was white.