In every aspect of life, a form of leadership exists, whether it is in the workforce, education, government, family or religious institutes. The Quran emphasizes the role and significance of leadership in Islam and God states,
“And remember the day on which we will call together all human beings with their leaders [imams].” (17:71)
Throughout his mission of propagation of the message of Islam, Prophet Muhammad had on several occasions named a successor who would lead after him; and more importantly, this commandment to name his successor came from God. God
commanded the Prophet,
“O Prophet! Proclaim what has been revealed to you from your Lord [the succession of Imam Ali], for if you do not, you will not have conveyed His message, and Allah will protect you from the people.” (5:67)
This historical revelation came upon the Prophet at a major crossroad between Mecca and Madina, called Ghadeer Khum.
The Prophet had just concluded making his first (and only) Hajj and was returning home, along with over 100,000 pilgrims, when he received the command by God to appoint Imam Ali as his immediate successor at his death.
After the Prophet had revealed the command before the people, the Quran then concluded with its last and final verse,
“This day, I have perfected your religion for you, completed my favor on you, and have chosen for you Islam as your religion.” (5:3)
All of the companions of the Prophet paid personal allegiance to Imam Ali and accepted him as the caliph after the Prophet.
However, seventy days after the monumental event, Prophet Muhammad left this world.
Disarray overtook some Muslims regarding who should succeed the Prophet as leader of the Muslim community. There were two main groups; one that consisted of the family of the Prophet (Bani Hashim) and prominent companions, and the other being a small group of companions of the Prophet.
The first group believed that the Muslim leadership had already been established by Divine ordinance which had been reiterated by the Prophet time and time again. This group later became known as the “Shia of Ali.”
The second group believed that the Prophet left the issue of succession open to the Muslim community to decide the leadership based on the concept of consultation (shura). Members of the second group had suggested that Imam Ali was too young (at the time of the death of the Prophet Muhammad, he was 33) to assume leadership. In addition, in their opinion, prophethood and succession (caliphate) should not be vested in one family.
In a hasty meeting at Saqifah Bani Sa’ida, Abu Bakr ibn Abi Quhafah assumed leadership (11 AH – 13 AH / 632 CE – 634 CE ). After Abu Bakr’s death, Umar ibn al-Khattab (13 AH – 23 AH / 634 CE – 644 CE) assumed leadership; followed by Uthman ibn Affan (23 AH – 35 AH / 644 CE – 656 CE). Afterwards, Ali ibn Abi Talib (35 AH – 40 AH / 656 CE – 661 CE) After the caliphate of Ali, two dynasties followed – the Umayyad and the Abbasid.
 Quran 5:67, 26:214, 5:55, 4:59.
 Sahih Bukhari, Book on Outstanding Traits, hadith #3430; Battles hadith #4064; Sahih Muslim, Book of the Merits of the Companions, hadith #4418; Al-Tirmidhi, Book on Outstanding Traits, #3664; ibn Majah, Book on the Introduction, 112 and 118; Musnad Ahmad ibn Hanbal 1:173, 175, 177, 179, 182, 184, and 185.
 The literal meaning of Shia is ‘followers’.