Umar (Arabic عمر بن الخطاب) (ca 586-90 – 644) also known as Umar ibn al-Khattab and Omar, was a great admirer and friend of the Muhammad, secondly only to the greatest companion of Prophet. He became the second caliph after Muhammad's death and ruled for 10 years playing a significant role in Islam.
Umar was born in Mecca in from 586-90 C.E. in the Banu Adi clan, which was responsible for arbitrations among the tribes. His father was Khattab ibn Nufayl and his mother was Hantammah daughter of Khattab, from the tribe of Banu Makhzum. He is said to have belonged to a middle class family. In his youth he used to tend to his father’s camels in the plains near Mecca. His father was famed for his intelligence among his tribe. He was a middle class merchant and is believed to be a ruthless and emotional pagan man who often treated Umar badly.
During Muhammad's era
Umar's hostility to Islam
In 610 Muhammad started delivering the message of Islam. Umar, alongside others in Makkah, opposed Islam and threatened to kill Muhammad. He resolved to defend the traditional, polytheistic religion of Arabia. He was most adamant and cruel in opposing Muhammad and very prominent in persecuting the Muslims. Umar was the first man who resolved that Muhammad had to be murdered in order to finish Islam. Umar firmly believed in the unity of the Quraish and saw the new faith of Islam as a cause of division and discord among the Quraish.
Due to the persecution at the hands of the Quraish, Muhammad ordered his followers to migrate to Abyssinia. As a small group of Muslims migrated Umar felt worried about the future unity of the Quraish and decided to have Muhammad assassinated.
Sunnis remember Umar as a rigid Muslim of a sound and just disposition in matters of the religion of Allah, a man they title Farooq, meaning "leader, jurist and statesman", and the second of the rightly-guided Caliphs. He patched his clothes with skin, took buckets on his two shoulders, always riding his donkey without the saddle, rarely laughing and never joking with anyone. On his ring is written the words "Enough is Death as a reminder to you O' 'Umar". He did not seek advancement for his own family, but rather sought to advance the interests of the Muslim community, the ummah. The general Sunni sentiment for Umar is summarized by one of Muhammad's companions, Abd Allah ibn Mas'ud:
Umar's submission to Islam was a conquest, his migration was a victory, his Imamate (period of rule) was a blessing, I have seen when we were unable to pray at the Kaabah until Umar submitted, when he submitted to Islam, he fought them (the pagans) until they left us alone and we prayed.—Abd Allah ibn Mas'ud, 
Umar is viewed very negatively in Shi'a literature and is regarded as a traitor to Muhammad, a usurper of Ali's rights, and a murderer. According to shia, his role during Muhammad's life time is questioned as he was not assigned to any civil or military authority. Some Shi'a writers have accused him of killing Muhammad's daughter Fatimah (see Fatimah's death). According to Shia Muslims, Fatimah, wife of Ali and daughter of Muhammad, was physically abused by him. These sources report that the event caused her to miscarry her child and eventually led to her death soon after. (see Umar at Fatimah's house).
- Al Farooq, Umar by Muhammad Husayn Haykal.chapter no:1 page no:51
- Armstrong, p. 128.
- Al Farooq, Umar, Muhammad Husayn Haykal Chapter no: 1 page no: 53
- Tartib wa Tahthib Kitab al-Bidayah wa al-Nihayah by ibn Kathir, published by Dar al-Wathan publications, Riyadh, Saudi Arabia, 1422 AH (2002) compiled by Dr. Muhammad ibn Shamil as-Sulami, page 168, ISBN 979-3407-19-6
- as-Suyuti, The History of the Khalifas Who Took the Right Way, p. 112
- Sayed Ali Asgher Razwy, Restatement of History of Islam and Muslims World Federation of KSI Muslim Communities, United Kingdom, ISBN 0 95 09879 1 3