The issue of the authority of the sunnah is a subject that many scholars have gave thought to and made various evaluations up to this day. The Sunnah is the words, acts and approvals of the Prophet who notify Islam to people. Due to the fact that Prophet's sunnah has an important place in understanding and practicing the religion of Islam, Muslim scholars have made different classifications in this subject since the first centuries. Recently, -in the XIX. and XX. century- Ibn 'Ashur (1879-1973), the scientist who lived in Tunisia and left influences in the Islamic world, has made a classification about the sunnah.