who should be the rightful successor to the Prophet Muhammad. The Sunni Muslims believed that Abu Bakr, Muhammad's close companion and father-in-law, should be the first caliph, or leader of the Muslim community. The Shia Muslims, on the other hand, believed that Ali, the cousin and son-in-law of the Prophet Muhammad, should be the first caliph, as they believed that the leadership should remain within the Prophet's family. This initial disagreement led to the development of two distinct branches of Islam, with differing beliefs and practices.
