The Quran is the sacred text of Islam. It is the literal word of Allah, the most divine authority and is incontestable and incorruptible. It is the first souce of guidance to any ethical dilemma, overrides any form of authority, and is uncorrupted as it is the final and literal word of Allah. It is the source of the five pillars and is used for informal (education, calligraphy, khutbah) and formal worship (salat, friday prayer). Muhammad received revelations from Allah over the course of 23 years in which his followers memorised it and was later put into the Quran.