The major distinction between the school of Ahlul Bayt and the other Islamic schools of thought revolves around the issue of Imamah, or the early succession to Prophet Muhammad. The school of Ahlul Bayt maintains that the office of the imamah is a divine office - meaning, the imam or khalifah (leadership) has to be appointed and given directly by Allah, for this office holds the same significance as that of prophethood. People are thus commanded by Allah to follow specific successors (imams) after the demise of the Prophet.
Other schools of thought say that the imamah is determined by shura (election) and that this method was used to determine the successor of the Prophet Muhammad. However, the Shi'a school of thought considers that the concept of shura was never fully enacted after the death of the Prophet because ibn Qutaybah asserts that the first caliph was nominated mainly by two people; Ibn Kathir says that he had confined the candidacy for the khilafah to 'Umar ibn al-Khattab and Abu 'Ubaydah ibn al-Jarrah, both of whom declined and nominated him, a nomination that was seconded by Ma΄adh, 'Usayd, Bashir, and Zayd ibn Thabit. Tabari narrates that the Ansar refused to submit to his allegiance in al-Saqifah (the place where the matter of immediate succession to the Prophet was discussed) and declared that they would only pay allegiance to Ali (because he was the one appointed by the Prophet to be his successor). The first caliph has been recorded to have said in his inaugural ceremony, “O people! I was appointed over you, but I am not the best one among you.” Historian ibn Abi al-Hadid al-Mu΄tazili records that the second caliph admitted his role in orchestrating the meeting at al-Saqifah when he later declared that paying allegiance to the first caliph had been a mistake (faltah) but that Allah had averted the disaster of it from the Muslims. The concept of shura however was not implemented during the second caliph's ascension to the caliphate since the first caliph appointed him before his death. It was not even enacted during the ascension of the third caliph to power, since he was also selected nominally by five people, but in essence by one—namely, the second caliph, who also appointed two governors to remain in power after his death namely: Sa΄d ibn Abi Waqqass and Abu Musa al-Ash΄ari.
Quranic Evidence for the Divine Ordination of the Imam
Numerous verses in the Noble Quran refer to the fact that throughout history Allah alone has the right to ordain an imam (leader) or khalifah for mankind - some of them are as follows:
O David! Verily We have placed you as a successor (khalifah) on the earth, so judge between men with truth and justice, and follow not your desires, for they will mislead you from the path of Allah.
And remember when the Lord of Abraham tried him with certain commands which he fulfilled. Allah said to him, 'Verily I am going to make you a leader (imam) for mankind.' Abraham said, 'And (what about) my offspring?' Allah said, 'My providence (does not) includes the wrongdoers.'
These verses clarify that not just anyone is entitled to assume the office of leadership or the imamah and one who qualifies for this is the one who Allah examines and he fulfills Allah's test. In particular, the Noble Quran in the above verse of 2:124 stresses very clearly that the wrongdoers (dhalimeen) are forbidden from assuming the leadership of the believers. Yet, does Islamic history show this command to have been carried out? How many caliphs and sultans during the Umayyad and Abbasid periods were corrupt and did not practice Islam properly, yet they were leaders of the Muslim nation?
Succession—khilafah or imamah—is appointed solely by Allah whenever it is mentioned in the Noble Quran. In the school of Ahlul Bayt, the khilafah refers not only to temporal power and political authority over the people but more importantly, it indicates the authority to do so. This authority must be from Allah since Allah attributes governing and judgment to Himself.
Seven Categories of Verses of Allah’s Government in the Quran
(1) The Verses of Kingdom:
(2) The Verses of Government:
(3) The Verses of Command:
It is not for a believer, man or woman, when Allah and His Messenger have decreed a matter that they should have any opinion in their decision. And whoever disobeys Allah and His Messenger, he has indeed strayed in plain error.
(4) The Verses of Guardianship:
Commentators unanimously agree that this particular verse refers to Imam Ali ibn Abi Talib who gave his ring to a beggar while in the state of bowing (ruku) in the course of his prayer.
By your Lord, they can have no faith until they make you (Prophet Muhammad) a judge in all disputes between them and find in themselves no resistance against your decision and accept it with full submission.
(5) The Verses of Following:
(6) The Verse of Choosing:
(7) The Verse of Judgment:
These examples from the Noble Quran show the characteristics of government which are only for Allah, the Exalted. The commonly repeated phrase ”a la lahu al-'amr wal-hukm” (is not the command and the judgment His?) also illustrates this point. The most important characteristics of the leadership of Allah are the guardianship and the command, and He bestows this virtue on whomever He wills. The nature of the khilafah gives the khalifah the privilege to be a guardian over the people and obliges them to obey him. Since the absolute obedience and surrender is only for Allah, then only Allah the Almighty has the right to transfer this power and authority to whomever He wills.
Allah says, “O you who believe! Obey Allah, and obey the Messenger, and those vested with authority over you ('ul ul-'amr minkum). And if you quarrel about something, refer it to Allah and the Messenger.” But if a person assumes leadership and becomes a caliph or imam by power and intimidation then he will not necessarily be entitled to be a legitimate Muslim leader. Logic dictates that the imam or caliph who succeeds the prophet should be appointed by Allah. Since Allah puts their obedience at the same level as obedience to Him and His Messenger, therefore not anyone is entitled to become the caliph of the prophet. Islamic history shows that some corrupt people assumed even the office of leadership and the khilafah during the Umayyad and Abbasid dynasties—then could this verse of obedience still apply to them? Would the believing Muslims have to follow these leaders blindly? Would Allah tell the Muslims to follow a corrupt leader and an oppressor?
In some of the hadith books, justification is found for such rulers to rule and a command for the Muslims to listen to them. Imam Bukhari narrates from the Prophet, “After me, there will be rulers (wilat), and you will find good ones and corrupt ones. You Muslims have to listen to both of them. Whoever breaks the unity of the whole (the jama΄ah) will be considered outside of the religion of Islam.” Such a hadith is not compatible with the Noble Quran, which says, “And incline not towards those who do wrong (dhalamu) lest the Fire touch you and you have no protector other than Allah, nor will you be helped.” The Noble Quran clearly emphasizes that those who believe should neither support nor incline towards an oppressor at all. There is no way to justify paying allegiance to or endorsing an oppressor to be the caliph or leader of the Muslim nation (ummah); doing so, would be in gross violation of the Quranic injunctions. Verse 4:59 not only commands the faithful to obey the 'Ul ul-'amr or their legitimate guardians (who are the infallible imams) but it also rectifies their infallibility since no corrupt or wrongdoing person could be entitled by Allah to assume this trust.
 Ibn Qutaybah, al-Imamah wal-Siyasah, Vol. 1, 6,
 Ibn Kathir, al-Sira al-Nabawiyyah, Vol. 2, 494
 al-Tabari Tarikh, Vol. 2, 443
 al-Suyuti, Tarikh al-Khulafa’, 69
 Ibn Abi al-Hadid al-Mu΄tazili, Sharh Nahj al-Balaghah, Vol. 2, 29
 Ibid., Vol. 9, 50
 Noble Quran, 2:30
 Noble Quran, 38:26
 Noble Quran, 2:124
 Noble Quran, 32:24
 Noble Quran, 3:26
 Noble Quran, 114:1-3
 Noble Quran, 5:18
 Noble Quran, 6:57
 Noble Quran, 6:62
 Noble Quran, 42:10
 Noble Quran, 3:154
 Noble Quran, 7:54
 Noble Quran, 13:31
 Noble Quran, 33:36
 Noble Quran, 5:55
 Noble Quran, 24:51
 Noble Quran, 4:64
 Noble Quran, 4:65
 Noble Quran, 3:31
 Noble Quran, 7:3
 Noble Quran, 28:68
 Noble Quran, 40:20
 Noble Quran, 4:59
 Sahih al-Bukharim, Kitab al-Imara, Hadith 1096, “The Book of Trials” Hadith 6530 and 6531, “Legal Judgments” Hadith 6610; Sahih Muslim, Kitab al-Imara, Hadith 3438; Musnad Ahmad ibn Hanbal, Part 1, 275, 297 and 310’ al-Darami, “The Book on Biographies” Hadith 2407
 Noble Quran, 11:113