Announced and illuminated to the public through the significant and decisive event of the Ghadir Khumm, the subject of Imamate and succession to the Messenger of Allah (PBUH) as an important ideological issue assumed a special status in Islamic studies. Throughout the history of Islam, many Islamic theosophists, historians and hadith experts have dealt with the subject and analyzed it in agreement with their own intellectual and ideological orientations. A noted Shiite work in the area of Ghadir Khumm studies which was intended to respond to questions on the event and to prove the ascendancy of Imam Ali (PBUH) in Imamate and succession through invoking Shiite and Sunni hadiths and historical accounts, especially accounts of caliphs’ virtues, is al-Mustarshid fi-l-Imama written by Muhammad ibn Jarir ibn Rustam al-Tabari, better known as al-Tabari the Great, a hadith expert in the third and fourth centuries AH. In this study, the author’s methods of reporting and criticizing the questions of deniers of guardianship after and succession to the Messenger of Allah (PBUH) and fake accounts of the virtues of the other three caliphs are examined with the analytic-descriptive method and through documentary research. The findings show that by categorizing the questions and doubts of deniers in al-Mustarshid fi-l-Imama al-Tabari the Great criticizes and responds to them using reliable evidence and documents, especially those from Sunni sources, to demonstrate Imam Ali (PBUH)’s ascendancy in the matter of succession to the Messenger of Allah (PBUH).
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