Musnad Ahmad 30:490

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from Yahya ibn Abi Kathir, from 'Ikrimah, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "If one of you prays in a single garment, let him cross its two ends over his shoulders."