Musnad Ahmad 30:2456

Yahya ibn Sa'id al-Qattan narrated to us, he said: Muhammad ibn 'Amr narrated to us, he said: Abu Salamah narrated to us, from Abu Hurairah, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) forbade two transactions in one transaction, and he forbade two ways of wearing clothes: that one of you should wrap himself in a single garment (al-samma'), or that one should sit with his legs drawn up to his abdomen (al-ihtiba') while wearing a single garment, with nothing between him and the sky."