The two groups also disagree on Ali's attitude towards Abu Bakr, and the two caliphs who succeeded him: Umar and Uthman Ibn Affan. Sunnis tend to stress Ali's acceptance and support of their rule, while the Shia claim that he distanced himself from them, and that he was being kept from fulfilling the religious duty that Muhammad had assigned to him. Sunnis maintain that if Ali was the rightful successor as ordained by God Himself, then it would have been his duty as leader of the Muslim nation to make war with these people (Abu Bakr, Umar and Uthman) until Ali established the decree.