Most of his followers, who became known as Sunni Muslims, felt that the faithful should base their decision on ability, and supported the Muslim elders’ choice of Muhammad’s father-in-law, Abu Bakr. But a small dissident group, who would eventually become known as Shia Muslims, were adamant that the new caliph should be a blood relative of the prophet, and thus decided that Muhammad’s son-in-law and cousin Ali ibn Abi Talib (the fourth caliph, according to Sunnis) was his rightful successor.