Historicity of Muhammad

While the existence of the Islamic prophet Muhammad is established by contemporaneous or near-contemporaneous historical records, attempts to distinguish between the historical elements and the ahistorical elements of many of the reports of Muhammad have not been very successful. Hence the historicity of Muhammad, aside from his existence, is debated. How much reliable history there is about Muhammad is disputed, with Muslim sources maintaining that "everything he did and said was recorded", while some academic sources claim that almost all of the available information about Muhammad's life, apart from the fact of his existence, is not historically credible.

Quotes

 * Far from Islam having been born in the full light of history, its birth was shrouded in what has appeared, to an increasing number of scholars, an almost impenetrable darkness. To be sure, there are very few scholars who would go so far as to claim that the Prophet never existed. Someone by the name of Muhammad does certainly appear to have intruded upon the consciousness of his near-contemporaries.
 * Tom Holland - In the Shadow of the Sword_ The Birth of Islam and the Rise of the Global Arab Empire-Doubleday (2012)