Abu Dawud Book 27, Hadith Number 4069.
Chapter : Turbans.
Narated By Abu Hurairah : The Apostle of Allah (PBUH) forbade wearing clothes in two styles: that a man sits in a single garment with his hands round his knees and uncover his private parts towards heaven and that he wears his garment while one of his sides is uncovered, and puts the garment on his shoulders.