ʿUMAR IBN AL-KHAṬṬĀB (assassinated AH 23/644 CE), second caliph and founder of the Muslim Arab empire. Born in pagan Mecca, he accepted the mission of Muḥammad as God's prophet before the emigration (hijrah) of that city's nascent Muslim community to Medina. Muḥammad later married his daughter Ḥafṣah, whose name is linked with the collation of the Qurʾān. ʿUmar's fame as caliph (634–644) justly rests on his energetic leadership and shrewd counsel during the expansion of the Medinan commonwealth, which was ultimately transformed into an imperial structure displacing both Byzantine and Persian power in the Middle East.

While traditional accounts attribute a great number of "firsts" to ʿUmar, modern scholars have not always been able to distinguish ʿUmar's achievements from those of...