Sunni and Shia Muslims disagree on the rightful successor to the Prophet Muhammad. Sunnis believe that Abu Bakr, the father-in-law of Muhammad, was the rightful successor, while Shias believe that Ali, Muhammad's cousin and son-in-law, should have been the successor. This disagreement has led to differing beliefs in terms of religious leadership and authority within Islam. Additionally, there are differences in certain religious practices and rituals between Sunni and Shia Muslims.
