Musannaf Ibn Abi Shayba 3:828

Mu'awiyah ibn Hisham narrated to us, he said: Sulayman ibn Qarm narrated to us, from Abu Fazara, from Abu Zayd, from Ibn Mas'ud, he said: "One should not pray in a single garment, even if it is wider than what is between the heaven and the earth, [unless] he prays while he is *mudtabi'* (having the garment wrapped around his body with one shoulder uncovered)."