Musnad Abu Ya'la al-Mawsili 110:143

Abdullah ibn Umar ibn Aban narrated to us, he said: Abd al-Rahim narrated to us, from Muhammad ibn Ishaq, from al-Husayn ibn Abdullah, from Ikrimah, from Ibn Abbas, who said: I saw the Messenger of Allah, may Allah bless him and grant him peace, on a rainy day, and he was protecting himself with a cloak that had mud on it when he prostrated.