Musnad Abu Ya'la al-Mawsili 112:30

Abu Khaythama narrated to us, Muhammad ibn al-Fadl narrated to us, Hammad narrated to us, from Habib ibn al-Shahid, from al-Hasan, from Anas ibn Malik, who said: The Messenger of Allah (may Allah bless him and grant him peace) went out intending [to go to] the mosque, while he was leaning upon Usama ibn Zayd, and he was wearing a cotton garment, having wrapped it around his body. Then he prayed with them.