Umar ibn Abd al-Aziz

Umar ibn Abd al-Aziz, known as Umar II, was the Umayyad caliph from 717 to 720. Remembered as the most pious of the dynasty, he sought to reform taxation so that non-Arab converts to Islam, the mawali, were treated as equals of Arab Muslims, ended the cursing of Ali from the pulpit and withdrew the army from the failed siege of Constantinople. His short reign became the model of a just ruler in later Sunni tradition.