In some respects, history of Islamic thought means history of conflicts of opinion. The fundamental conflict between Ahl as-Sunnah and Shia is around the subject of Imamat. According to Shia, where begun the subject of Imamat, Omar's function was extremely negative. So, It's impossible to find in the Shiite books any good expression about Omar. Whereas Omar is one of the nearest persons to the Prophet Muhammad according to Ahl as-Sunnah. Besides, relationship between Omar and Ali was exceedingly positive. In fact, Shia is distorting the historical realities and is showing events that never happened as if they happened. In this point we have to say that those rumors never exist in any source book except Shiite books. Naturally, Ahl as-Sunnah never accept Shiite rumors that contain very bad expressions about Omar. So, this article deals with some subjects such as the matter of Fedek Territory, Omar's marriage with Ali's daughter Umm al-Kulthum, how is the Shi’ite approach to the character of Omar and the fact that Ahl al-Bayt mention Omar only in an auspicious manner. In spite of some troubles between Omar and Ali as a usual fact, the relationship between them was always positive. Finally, this article aims to contribute to the fraternity between Ahl as-Sunnah and Shia.