The Arabic word mujaddid means "reformer", "renovator", "reviver", "renewer" or "regenerator". It is someone who revives and renovates the religion. The concept of tajdid (renewal or revival) and the term mujaddid come rather from a hadith, a statement of the Prophet Muhammad. This hadith was written down by Abu Dawood in his Sunan, one of the six authoritative Sunni collections of the Prophet's statements. In this hadith, the Prophet says: