Abu Dawud mentioned in his Sunan that the Prophet is related to have said, "The difference between us and the profane is that we wear the 'imama (turban) on top of the qalansuwa." 

The material of the turban is ideally white or green, and of a very fine cotton. However, the colours and length of the turban vary. 

All of the founding Imams of the four schools of Ahl al-Sunnah wal-Jama'ah wore the turban. Such is the high nobility of the turban that we are told even the angels wore it. Of the Qur'anic verse, "Your Lord shall help you with five thousand angels bearing marks" (Surat Ali 'Imran, verse 125), Ibn 'Abbas, the greatest of the early exegetes, said: "The signs are that they wore turbans."