Umar ibn al-Khattab (c. 584-644) is, after Abu Bakr, the most commanding of the early figures of Islam. The tradition remembers him first as a fierce opponent of the new faith who underwent a dramatic conversion, in the best-known account, softened on finding his own sister reciting the Qur'an, and became thereafter one of its most formidable adherents. He carries the honorific al-Faruq, the one who distinguishes truth from falsehood.
The evidence for his life is the same sira and hadith literature that supplies the rest of early Islamic history, set down generations later in the collections of al-Bukhari and Muslim and in the great chronicles, and subject to the same source-critical cautions. Across it Umar is drawn as a man of towering severity and personal austerity, plain-living to the point of legend, quick to anger and equally quick to justice, and so respected by the Prophet that a well-known tradition has Muhammad say that if there were to be a prophet after him it would be Umar.
On the Prophet's death he was the decisive voice in securing the acknowledgement of Abu Bakr as caliph, and when Abu Bakr died in 634 he named Umar to succeed him.