Umar

Umar ibn al-Khattab (; ), also spelled Omar, was the second Rashidun caliph, ruling from August 634, when he succeeded Abu Bakr () as the second caliph, until his assassination in 644. Umar was a senior companion and father-in-law of the Islamic prophet Muhammad. Umar has been called instrumental in the expansion of the Islamic world beyond Arabia.

Umar initially opposed Muhammad, who was his distant Qurayshite kinsman and later became his son-in-law. However, after his conversion to Islam in 616, Umar became the first Muslim to openly pray at the Kaaba. He participated in nearly all the battles and expeditions under Muhammad, who bestowed upon him the title ''al-Fārūq'' for his sound judgments. Following Muhammad's death in June 632, Umar pledged allegiance to Abu Bakr () as the first caliph and served as his closest adviser. In August 634, the dying Abu Bakr nominated Umar as his successor.

Under Umar, the caliphate expanded at an unprecedented rate, conquering the Sasanian Empire and more than two-thirds of the Byzantine Empire. His attacks against the Sasanian Empire resulted in the conquest of Persia in less than two years (642–644). According to Jewish tradition, Umar set aside the Christian ban on Jews and allowed them into Jerusalem and to worship. Umar was assassinated by the Persian slave Abu Lu'lu'a Firuz in 644.

Umar is generally viewed by historians as one of the most powerful and influential Muslim caliphs in history. In Sunni Islamic tradition, he is revered as a just ruler and a paragon of Islamic virtues, with some hadiths identifying him as the second greatest of the Sahabah after Abu Bakr. However, he is viewed negatively in the Twelver Shia tradition. Provided by Wikipedia