Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) "forbade two ways of dressing and two kinds of sale: he forbade al-mulamasah and al-munabadhah; and that a man should sit with his knees drawn up (ihtiba') in a single garment with nothing of it over his private parts; and that a man should wrap the single garment around himself on one of his sides."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الجمعة / 5918