Sunni Muslims agree with the position taken by many of the Prophet's companions, that the new leader should be elected from among those capable of the job. This is what was done, and the Prophet Muhammad's close friend and advisor, Abu Bakr, became the first Caliph of the Islamic nation.Shia Muslims believe that following the Prophet Muhammad's death, leadership should have passed directly to his cousin/son-in-law, Ali.

Shia Muslims also feel animosity towards some of the companions of the Prophet Muhammad, based on their positions and actions during the early years of discord about leadership in the community. Many of these companions (Abu Bakr, Umar, Aisha, etc.) have narrated traditions about the Prophet's life and spiritual practice. Shia Muslims reject these traditions (hadith) and do not base any of their religious practices on the testimony of these individuals. This naturally gives rise to some differences in religious practice between the two groups. These differences touch all detailed aspects of religious life: prayer, fasting, pilgrimage, etc.