The text suggests that Ali's succession as the fourth Caliph was legitimized through a combination of factors, including:1. Consensus among senior companions and other notable figures in Madinah2. Absence of alternative candidates3. Support from respected individuals such as Thalhah and Zubair4. Perception of his leadership qualities by the Muslim community due to his piety, courage, and wisdom5. Historical context, including the political and social landscape of the time, which created an opportunity for Ali to emerge as a leader and for the Muslim community to desire stability and continuity in leadership.Overall, the text suggests that Ali's legitimacy as the fourth Caliph was due to a combination of factors that contributed to his recognition as a leader within the Muslim community.