The Prophet's death was unbelievable for some Muslims. A man arose in the name of Allah; he united the scattered and disunited Arabia, which had never experienced tranquility since then. He made a government based on faith. He abolished the civil war among the tribes of Arabia and succeeded peace for it. How would such a great man die? 'Umar got up among the Muslims assembled at the gate of the mosque and said, “Some of the hypocrites claim that the Apostle is dead, but by God he is not dead. He has gone to his Lord as Moses the son of 'Imran went before, and was hidden from his people for forty days, returning to them after it was said that he had died. But by God the Apostle will return as Moses returned and will cut off the hands and feet of the men who claim that the Apostle is dead.”1
Nevertheless, the Messenger of God (S.A.W.A.) had departed to the dominion of his Lord, and he was not among his people any more. He was the “Seal of the Prophets” or the “Last of the Prophets” and there was no prophet after him. Who was the leader of the community after him?
The Sunnites believe that,
“Caliphate is offspring of the society and all of the four rightly-guided caliphs came to power by people's votes. Islam has entrusted the election of the caliphs and the control of the community to a council of the learned and devoted Muslims, thus the Messenger of God did not explicitly appoint his successor. Had he designated one, people would have put in doubt about him, or they might not have accepted him so they would have apostatized. God wanted to prevent people from apostasy; therefore, He did not appoint one (though some became apostatized).
The successor would be the same as a prophet who is raised up by God; however, Muhammad (S.A.W.A.) was the 'Last of the Prophets'. Had he designated a successor, he would have deprived people of their own rights and it would have led to the reign of tyrants and God would have been responsible for it.”2
When Abu Lu'lu'a Fayruz assassinated 'Umar b. al-Khattab and Hafsa heard her father thinking of putting no one as the caliph after his death, she told him, “If you had a shepherd looking after your sheep and if he had left his duty, you would have regarded him as a waster, so consider people becoming worst.” 3 While some sheep cannot be left without a shepherd, how could the Messenger of God leave his community without a leader?
We believe that 'Ali b. Abi Talib was the only man among the Prophet's Companions who neither worshipped any idols nor committed any sins in his life during the paganism and Islam. He was the first man who believed in the Messenger of God (S.A.W.A.) and prayed with him.4 From his early childhood, he was continuously with the Messenger of God (S.A.W.A.) and would follow him “like a young camel following in the footprints of its mother”.5
He was the most meritorious, the most pious, the most learned, the noblest, the bravest, and the nearest man and kinsfolk to the Prophet (S.A.W.A.) among his Companions. The Messenger of God took him as his brother and God identified him as the soul of the Prophet.6
He was one of the Household of the Prophet (ahl al-bayt) whom God purified with a thorough purification, ﴾Indeed Allah desires to repel all impurity from you, O People of the Household, and purify you with a thorough purification.﴿ (Q: 33/33).7
Thus, the Messenger of God (S.A.W.A) appointed him as his successor and his executor. He proclaimed it explicitly and implicitly in many cases, therefore we believe him as the immediate successor to the Prophet.
God raised the prophets to preach the word of Allah and guide people to the straight path; to establish a government was subordinate. Muhammad (S.A.W.A.) was the Messenger of God whether he was under the pressure and torture of Quraysh in Mecca, or he was the religious and political leader of his community in Medina. Jesus who was wandering in plains and mountains and did not have a permanent residence was a prophet, as Solomon who ruled a vast and unique kingdom was. 'Ali b. Abi Talib was the immediate successor to the Prophet (S.A.W.A.), whether he was in power, or deprived of it.
This is the dispute between the Shi'ite and the Sunnite. Now we need an arbiter to make judgment between us, an arbiter whom both of us accept and believe in. Moreover, who is better than God and His apostle? God says, ﴾O You who have faith! Obey Allah and obey the Apostle and those vested with authority among you. In addition, if you dispute concerning anything refer it to Allah and the Apostle, if you have faith in Allah and the Last Day. That is better and more favorable in outcome.﴿ (Q: 4/59).
So, let us consider what God and his Apostle say about the past prophets' successors in general and about Muhammad's successor in particular.8
The Holy Qur'an places great emphasis on the duty of all Muslims to maintain the bonds of blood relationship. ﴾Indeed Allah enjoins justice and kindness, and generosity towards relatives, and He forbids indecency, wrong and aggression. He advises you, so that you may take admonition.﴿ (Q: 16/90).
It contains specific instructions about the maintenance of kinship ties and inheritance as well as stories and statements about the succession of the past prophets and their families, matters, which cannot be relevant to the succession to the Messenger of God (S.A.W.A.)
In the story of the past prophets, as it is related in the Holy Qur'an, their families play a prominent role. The families provide vital assistance to the prophets against the adversaries among their people. After the death of the prophets, their descendants became their spiritual and material heirs. The prophets ask God to grant them the help of members of their family and they pray divine favor for their kin and their offspring.
The prophets of Banu Isra'il were in fact all descendents of a single family from Adam and Noah down to Jesus. ﴾Indeed Allah chose Adam and Noah, and the progeny of Abraham and the progeny of 'Imran above all the nations; some of them are the descendents of the others, and Allah is All-hearing, All-knowing.﴿ (Q: 3/33-4).
After narrating the story of Moses, Isma'il and Idris, the Holy Qur'an adds, ﴾They are the ones whom Allah has blessed. From among the prophets of Adam's progeny, and from [the progeny of] those We carried with Noah, And from among the progeny of Abraham and Israel, and from among those We guided and chose.﴿ (Q: 19/58).
The chain of the prophets and their families is described with more detail in the following verses. ﴾And We gave him Isaac and Jacob and guided each of them. And Noah We had guided before, and from his offspring, David and Solomon, Job, Joseph, Moses and Aaron -thus do We reward the virtuous- and Zechariah, John, Jesus, and Ilyas, -each of them among the righteous- and Ishmael, Elisha, Jonah and Lot -each We graced over all the nations- and from among their fathers, their descendants and brethren. We chose them and guided them to the right path. That is Allah's guidance: with it, He guides whomever He wishes of His servants. Nevertheless, were they to ascribe any partners [to Allah], what they used to do would not avail them. They are the ones whom We gave the Book, the judgment and prophet-hood. So if these disbelieve in them, We will have certainly entrusted them to a people who will never disbelieve in them.﴿ (Q: 6/4-89).
Abraham was the patriarch of the prophets of Banu Isra'il. All later prophets and transmitters of the scripture among them were of his descendants, ﴾Certainly We sent Noah and Abraham and We ordained among their descendents, Prophet-hood and the Book.﴿ (Q: 57/26).
In the face of the opposition of Banu Isra'il, Moses implored his Lord to grant him the help of his brother Aaron, ﴾Appoint for me a minister from my family, Aaron my brother. Strengthen my back through him, make him my associate in my affair, so that we may glorify You greatly, and remember You greatly.﴿ (Q: 20/29-34). God responded to his prayer, ﴾Certainly, We gave Moses the Book and We made Aaron, his brother, accompany him as a minister.﴿ (Q: 25/35).
When the angels announced to Abraham the imminent birth of his son Isaac and, after him his grandson Jacob, his wife Sarah doubted the good news in view of their advanced age. However, the angels reminded her of her elevated rank as the spouse of Abraham. ﴾His wife, standing by, laughed as We gave her the good news [the birth] of Isaac, and Jacob after Isaac. She said, 'O, my! Shall I an old woman, bear [children], and [while] the husband of mine is an old man? That is indeed an odd thing!' They said 'Are you amazed at Allah's dispensation? [That is] Allah's mercy and His blessing upon you, Members of the household.' ﴿ (Q: 11/71-73).
Muhammad (S.A.W.A.) was not different from his precedent prophets, ﴾A precedent of those We have sent from among Our Apostles before you, and you will not find any change in Our precedent.﴿ (Q: 17/77).
Insofar as the Holy Qur'an expresses the thoughts of the Prophet (S.A.W.A.), it is evident that he could not have considered Abu Bakr his natural successor or have been pleased by his succession. Yet he could not have seen his succession essentially other than in the light of the narrations of the Holy Qur'an about the succession of the earlier prophets, just as he saw his own mission as a prophet, the resistance of his people with which he met, and former prophets as related in the Holy Qur'an.
These earlier prophets considered a supreme divine favor to be succeeded by their offspring, or close kin for which they implored their Lord. The eminent position of the families and the descendents of the past prophets and the parallelism often observed between the history of the former prophets in the Holy Qur'an and that of Muhammd (S.A.W.A.) should arise from expectations of a distinguished place reserved for his family. The kin of the Messenger of God are mentioned in various contexts, sometimes probably in a wider sense than that of his family.
This order is addressed to the Prophet in Warning Verse (aya indhar),9 and in the following verse, ﴾Say I do not ask of you any reward for it, except the affection for [my] relatives.﴿ (Q: 42/23). There is also the verse of the 'mutual imprecation' (mubahala) (Q: 3/61). The Prophet (S.A.W.A) came with 'Ali, al-Hasan, al-Husayn and Fatima to discuss a delegation of Christians from Najran. In this verse, God identifies 'Ali as the soul of the Messenger of God (S.A.W.A.). Moreover, He refers to 'Ali, as the successor to the Prophet, in the Guardian Verse (aya wilayat) as follow, ﴾Your guardian is only Allah, His Apostle, and the faithful who maintain the prayer, and give the zakat while bowing down.﴿ (Q: 5/55). 10
The Prophet (S.A.W.A.) usually appointed commanders and ordered them to raid to the polytheist tribes or he sent representatives to the kings and invited them to Islam, but he never sent Abu Bakr for a delegation. He only once entrusted him with the “Renunciation Chapter” to proclaim it to the people in Mecca, while God sent down the Gabriel and ordered the Prophet that he or a man of his own should proclaim it.11
These are the reasons why we believe 'Ali b. Abi Talib is the immediate successor to the Prophet (S.A.W.A.), however, our brother disapproves them.