"The text (the Qur’an), however, came into being not in order to systematize the superstructure of the Islamic state but to systematize a less-institutional arrangement of the social life to which the Prophet was told he was a “witness” (shahed). Thus, in contrast to its elaborate rules on the problems it recognized as such in its immediate historical surroundings, the Qur’an never spelled out any direct proposals on how a state was to be governed, and so these rules had to be extrapolated from various prophetic and Qur’anic judgments. This lack is evident in the succession of the first four caliphs: After each one passed away, a different method was used for selecting a successor. (Each of those methods, however, emphasized the assent [bay’ah] of the community of believers.) It was only after the fourth caliph, ‘Ali, during whose reign it was becoming obvious that the Muslim ummah, demographically magnified, territorially expansive, and ideologically factionalized, was not likely to assent in its entirety to any single subsequent ruler that a forcible takeover of the state machinery was undertaken by the Umayyads, whereafter a hereditary rule of succession was invoked."
— Mohammed A. Bamyeh,The Social Origins of Islam: Mind, Economy, Discourse.