The Shia propagandists oftentimes abuse the following Hadith in order to claim that the Prophet appointed Ali ibn Abi Talib as his successor:

Sahih al-Bukhari, Volume 5, Book 59, Number 700:

Allah’s Apostle set out for (the Battle of) Tabuk, appointing Ali as his deputy (in Medina). Ali said, “Do you want to leave me with the children and women?” The Prophet said, “Will you not be pleased that you will be to me like Haroon to Musa? But there will be no prophet after me.”

However, this Hadith is not evidence for the Caliphate of Ali after the death of the Prophet because the comparison made was between Ali and Prophet Haroon. It is well-known that Prophet Haroon died before Prophet Musa, and thus was never his successor after him.

The following is an explanation by Imam al-Qurtubi in his Tafseer:

There is no disagreement that Haroon died before Musa…and (Haroon) was not a successor after him (Musa), for the successor (to Musa) was Yusha bin Noon (i.e. Joshua), so if he (the Prophet) wanted by his saying (to grant Ali) the Caliphate, he would have said “you will be to me like Yusha was to Musa”, so when he didn’t say this it proved that he didn’t want that meaning, but he (simply) wanted that “you are my deputy over my family in my life and my absence from my family, like Haroon was deputy of Musa over his people when he left to speak to his Lord.”

Sayyid Mujtaba Musavi Lari, a Shia scholar, says

“He (Allah) appointed Harun the helper, assistant, deputy and successor of Musa among his people, and even made him a prophet…Since Harun was the leader of all the Bani Isra’il, the situation of Ali, peace be upon him, was analogous.

source: Imamate And Leadership, http://home.swipnet.se/islam/books/imamate/lesson5.htm

This is simply incorrect: Prophet Haroon died before Prophet Musa, so it is impossible to claim that Haroon was the successor of Musa. The successor of Prophet Musa was Prophet Yusha (Joshua) and therefore if the Prophet had wanted to imply successorship, then surely he would have likened Ali to Prophet Yusha.

In Hadith al-Manzilah it is narrated that the Prophet left to go for war and he deputized Ali as the caretaker of his family in his absence. It was very routine at that time for a father to deputize his son as caretaker of the family in his absence; because the Prophet did not have a son, Ali was the most appropriate choice for this very noble task.

Sayyid Mujtaba Musavi Lari, a Shia scholar, says

“ To this we answer that whenever the Prophet, peace and blessings be upon him and his family, left the Islamic capital, he would always appoint someone to act as his deputy. If by comparing Ali, peace be upon him, to Harun, the Prophet, peace and blessings be upon him and his family, had intended nothing more than the usual appointment of a deputy, restricted in his authority to Madinah for the period of the Prophet’s absence, why did he not use a similar expression for those other favored Companions he would appoint as deputy? Why did he not use the same or similar words to describe the services they rendered?

source: Imamate And Leadership, http://home.swipnet.se/islam/books/imamate/lesson5.htm

In order to respond to this, we must first understand the context in which this Hadith was said. Before the Battle of Tabuk, a band of the Munafiqoon (Hypocrites) began to spread anti-Islamic propaganda in order to dishearten the Muslims. One of the lies they spread was directed towards Ali ibn Abi Talib and it was because of this that the Prophet said what he said in the Hadith. We read:

Expedition to Tabuk

…The Munafiqoon were constantly in league with the Jews of al-Medinah and were holding regular consultations against the Muslims. A band of twelve Munafiqoon built their own separate mosque as a center for carrying out their hostile activities and anti-Islamic propaganda, and for creating a rift among the Muslims. When they saw the Muslims engaged in preparing for the impending battle, they started passing discouraging remarks…

Islamic Army’s Departure

The Messenger of Allah set out for Tabuk with an army of 30,000 men from al-Medinah…and he put Muhammad bin Maslamah Ansari in charge of al-Medinah…The Prophet had left behind Ali to look after his family. The Munafiqoon used this as an opportunity to spread false rumors about Ali. They implied that the Prophet gave little importance to Ali and therefore left him alone in al-Medinah. When his patience ran out, he (Ali) hurried from al-Medinah and–joining the Prophet at al-Jurf–asked: “The Munafiqoon are saying such-and-such about me and so I have come to you.” The Prophet of Allah said: “They are liars. I have left you behind to look after my household, so go back.” In order to soothe his feelings, the Prophet further added: “You are to me as Haroon was to Musa, except that there will be no Prophet after me.” Ali returned to al-Medinah pacified and satisfied.

(Tareekh al-Islam, Vol.1, p.232)

This context is understood by the Shia as well:

Al-Islam.org says

The Expedition of Tabuk

…The hypocrites in Medina seized this opportunity to plant disaffection in the minds of the neophytes in Islam. They not only did not take part in the campaign but also tried to dissuadeothers from doing so. In an attempt to undermine the will and purpose of the Muslims, they began to spread alarmist stories…

Nevertheless, many Muslims responded to the appeal of the Prophet, and took up arms to defend the faith. When a head-count was taken, there were found to be 30,000 volunteers. It was the largest force ever assembled in Arabia until then.

The Prophet appointed Ali ibn Abi Talib his viceroy in Medina during his own absence…For the hypocrites, there was nothing more disagreeable than to see Ali in authority over them. When the army left Medina, they began to whisper that the Apostle had left Ali in Medina because he wanted to get rid of him. Ali was mortified to hear that his master had found him a “burden.” He, therefore, immediately went after the army and overtook it at Jorf. The Apostle was surprised to see him but when he (Ali) explained why he came, he (the Apostle) said:

“These people are liars. I left you in Medina to represent me in my absence. Are you not content to be to me what Aaron was to Moses except that there will not be any prophet after me.”

source: Restatement of History of Islam, http://al-islam.org/restatement/34.htm

Sayyid Mujtaba Musavi Lari, a Shia scholar, says

“ …they (the Munafiqoon) began spreading idle rumors in the hope of weakening Ali’s position. They hinted that the Prophet, peace and blessings be upon him and his family, was angry with Ali, peace be upon him, and that it was for this reason that he had not been permitted to accompany him on a major military expedition.

Ali, peace be upon him, was greatly troubled and saddened by the circulation of these rumors, and he hastened to the presence of the Prophet, peace and blessings be upon him and his family, who had already left Madinah. He told him what had happened, and with a single historic sentence he clarified the special position of Ali, peace be upon him, once and for all:

“Are you not content that your relation to me shall be like the relation of Harun to Musa, excepting only that there shall be no prophet after me?”

source: Imamate And Leadership, http://home.swipnet.se/islam/books/imamate/lesson5.htm

Now we come back to the question of the Shia propagandist which was: “Why did he (the Prophet) not use the same or similar words to describe the services they (the other Sahabah) rendered (i.e. for similar tasks)?” The answer is obvious: the Munafiqoon did not spread this particular rumor except against Ali. It was this degrading rumor and Ali’s concern that caused the Prophet to say what he said in order to placate Ali. Had other Companions been similarly slandered, then perhaps they too would have refused to stay back in Medinah.

Because these other Sahabah did not feel dismayed with their deputyship and did not ask to go along with the Prophet instead of staying behind, there was thus no need for the Prophet to reassure them with such words as he used for Ali. On the other hand, when Ali was deputized by the Prophet to take care of his family, the Munafiqoon implied that this task was menial as it left Ali behind with women and children. This is the reason that Ali asked to go along with the Prophet instead. It was based on this specific concern of Ali’s (i.e. that the task was menial) that the Prophet spoke the words he did, in order to convey to Ali the extreme importance of taking care of his family in his absence.

Hadith al-Manzilah was said to Ali because of the circumstances, which were that Ali objected to staying behind with children and women as opposed to embarking on Jihad with the Prophet. By saying those words, the Prophet was explaining to Ali how he would be to him, by staying behind watching over women and children, like Haroon was to Musa when the latter left the former behind as a deputy over his people. The Prophet’s purpose in saying this was to reassure Ali that this deputyship was an honor and that he would not be any less than the ones who went to fight in battle.

Al-Islam.org says

“The Prophet appointed Ali ibn Abi Talib his viceroy in Medina during his own absence. He selected Ali to be his viceroy for the following reasons: He wanted to show to the rest of the world that he considered Ali to be more qualified than anyone else to be the ruler of all Muslims, and to be the head of the Islamic State. He, therefore, appointed him as his representative in his capital.

source: Restatement of History of Islam, http://al-islam.org/restatement/34.htm

This is a very odd argument. This was the singular instance in which the Prophet left Ali as his deputy in Medinah, yet we know that there were many other battles in which the Prophet left other Sahabah behind as his deputy in Medinah. For example, the Prophet left behind Muhammad bin Maslamah Ansari as his deputy in Medinah; what if we told the Shia that this is a proof that the Prophet “wanted to show to the rest of the world that he considered Muhammad bin Maslamah Ansari to be more qualified than anyone else, to be the ruler of all Muslims, and to be the head of the Islamic state and the Prophet therefore appointed him as his representative in his capitol?”

To this, the Shia would say that this is a preposterous argument, yet suddenly they force this argument upon us in the one single instance in which the Prophet appointed Ali as his deputy. Therefore, we say to the Shia that their interpretation is just as preposterous as saying that the other Sahabah were appointed as Caliphs by the Prophet simply because he deputized them.

Shaykh al-Islam Ibn Taymiyyah wrote in Minhaj as-Sunnah:

As for the Messenger placing Ali in charge over Medinah, then that is not an honor specific to him alone. He (the Prophet) had left Ibn Makhtoom, Uthman bin Affan, and Abu Mundhir (in charge of Medinah, i.e. on other occasions). This (being appointed over Medinah) is not an unrestricted succession, which is why none of these people ever said they were the Caliph of Allah’s Messenger…Ali left Medinah along with the Prophet to Badr, Hunayn and other places, and (the Messenger) left others in Medinah as deputies.

(Minhaj as-Sunnah)

Shia says

“The words “except there will be no prophet after me” indicates that Ali was being appointed for a task similar to Prophethood. Otherwise, there would have been no need to mention Prophethood at all.

One of the fundamental beliefs of Islam is that Prophet Muhammad was the final seal of the Prophets. Therefore, whenever Prophet Muhammad would liken anyone to a Prophet, he would make sure to clarify that this is only a comparison and does not mean there will be any Prophet after him. In a separate instance, the Prophet praises Umar as one who is very much inspired as Prophets were inspired, but he makes sure to clarify for the people that there would be no Prophet that would succeed him. These were clarifications that were necessary in order that people not be misguided on the matter later lest they take Ali or Umar as Prophets.

In any case, to end the discussion altogether, Prophet Haroon and his lineage were prohibited by the Law of Musa to take executive roles, but they were instead limited to religious, spiritual, and ceremonial roles. It was Prophet Yusha (Joshua) who became the Caliph (successor) of Musa, not Prophet Haroon nor his descendants. Throughout the Caliphate of the Shaykhayn and Uthman, Ali remained a spiritual guide for the people. Similar is the case with many of the Imams of the Shia, who secluded themselves from any temporal role and instead remained as spiritual guides.

The Hadith al-Manzilah does not at all help the Shia cause, but rather it is a strong proof against the Shia claims. Had the Prophet wished to imply that Ali was his successor, then he would have likened Ali to Prophet Yusha rather than Prophet Haroon. Instead, the Prophet likened Ali to Prophet Haroon whose role was not that of a temporal ruler but that of a spiritual guide.