Umar b. al-Khattab

Umar, also spelled Omar (عمر بن الخطاب‎ ʻUmar ibn al-Khaṭṭāb, "Umar, Son of Al-Khattab"; c. 584 CE – 3 November 644 CE), was a senior companion of the Prophet Muhammad. He was appointed by Abu Bakr to succeed him and occupied the position of caliph till his death.

21 Questions

In the past Iran was a superpower that defeated the Roman Empire. Umar's army defeated Persia and made it Muslim by force. Had he not done so, would Iran, most probably, have remained a Zoroastrian nation today? Sayyed Mohammad Al-Musawi	Did Umar somehow know that the Prophet (s) had asked Imam Ali (as) not to use his sword to claim his right after the death of the Prophet (s)? Sayyed Mohammad Al-Musawi
When Umar refused giving the pen to the Prophet (saw) who wished to write down the important message, was Imam Ali present in the room at that time? If so, why did he not offer the pen? Sayyed Mohammad Al-Musawi	Did Imam Ali (as) try to prevent the practice of Tarawih prayers during the reign of Umar bin Khattab? Sayyed Mohammad Al-Musawi