In The Holy Quran

The Quran is the central religious text of Islam and Muslims believe that it represents the words of God revealed to Muhammad through the archangel Gabriel.^[28][29][30]
Although it mentions Muhammad directly only four times,^[31] there are verses which can be interpreted as allusions to Muhammad's life.^{[17][n 3]} The Quran however provides little assistance for a chronological biography of Muhammad, and many of the utterances recorded in it lack historical context.^[32][33]

Early biographies

Main article: Prophetic biography

Next in importance are historical works by writers of the 2nd and 3rd centuries of the Muslim era (A.H. -- 8th and 9th century C.E.).^[34] These include the traditional Muslim biographies of Muhammad (the sira literature), which provide further information on Muhammad's life.^[35]
The earliest surviving written sira (biographies of Muhammad and quotes attributed to him) is Ibn Ishaq's Life of God's Messenger written ca. 767 CE (150 AH). The work is lost, but was used verbatim at great length by Ibn Hisham and Al-Tabari.^[36][37] Another early source is the history of Muhammad's campaigns by al-Waqidi (death 207 of Muslim era), and the work of his secretary Ibn Sa'd al-Baghdadi (death 230 of Muslim era).^[34]
Many scholars accept the accuracy of the earliest biographies, though their accuracy is unascertainable.^[36] Recent studies have led scholars to distinguish between the traditions touching legal matters and the purely historical ones. In the former sphere, traditions could have been subject to invention while in the latter sphere, aside from exceptional cases, the material may have been only subject to "tendential shaping".^[38]

^{Ref:  http://en.wikipedia.org/wiki/Prophet_Muhammad}