Musnad Ahmad 32:1566

Hassan narrated to us, Hammad ibn Salamah narrated to us, from Humayd, from Anas and al-Hasan: "The Messenger of Allah (peace and blessings of Allah be upon him) went out leaning upon Usamah ibn Zayd, and he was wearing a cotton garment, having crossed its two ends over one another, and he led them in prayer."