Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that the Messenger of Allah (peace and blessings be upon him) said: "I have been commanded to prostrate on seven parts and that I should not gather my hair or clothes."
Hadith Referenceصحيح ابن خزيمه / جماع أبواب اللباس فى الصلاة / 782