Musnad Ahmad 304:7

Yahya ibn Ishaq narrated to us, he said: Al-Layth ibn Sa’d narrated to us, from Yahya ibn Sa’id, from Abu Umamah ibn Sahl, from ‘Umar ibn Abi Salamah, who said: "I saw the Messenger of Allah, peace and blessings of Allah be upon him, praying in a single garment, having crossed its two ends, placing its two ends upon his shoulders."