However...
However, from all canons of justice we are constrained to believe that the 67th verse of the Surah al-Ma'idah bore a message of utmost importance and that was regarding the succession of the Holy Prophet and the leadership of an infallible Imam for guiding the Muslim Ummah. Many such notable companions of the Holy Prophet who are held in very high esteem of all the Muslims and are popular among them have narrated this event of Ghadir-i Khum which pertains to the succession of the Holy Prophet.
Imamate is One of the Fundamentals of Faith 1 . In the verse of the Holy Qur'an quoted above Allah reminds the Holy Prophet that if he did not make an announcement regarding the appointment of his successor for the security of the society from the evils of the hypocrites and disruptionists, he would not fully justify his mission of conveying to the people the message of Allah.
In view of the strong wording of the relevant verse of Surah al-Ma'idah and his lifelong teachings, we consider the appointment of the successor as an integral factor of religion. 2. There are 29 hadith in Wassa'ilush Shi'ah , vol. I and 17 hadith in Mustadrakul Wasa'il which establish that the basis of Islam rests an a few principles, and the most important among them is that of Wilayat (the succession of the Holy Prophet). We should like to explain this principle.
Imam Muhammad Baqir says: "The basis of Islam depends on Prayers, zakat , hajj , fasting and wilayat ". Zurarah, a devoted follower and companion of the Holy Imam asked him, "Out of these fundamental principles which one is most important". The Holy Imam replied, " Wilayat is the most important of all". Thereafter, he elaborated, "Since succession or mastership is the key to prayers, fasting and hajj , the successor or the vicegerent is supposed to be the leader and guide".
Thus by succession it is meant that the infallible Imam or the vicegerent and successor to the Holy Prophet must be followed and obeyed. In certain narrations Walayat or succession means obedience of the infallible Imam. It is interesting to note that in case of prayers, fasting, hajj and zakat each one is affected by physical or financial reasons but the principle of accepting the authority of the Imam remains intact in all circumstances.
Besides, it can be further explained that the Holy Prophet never before assembled the people at one place nor did he proclaim his message about prayers, hajj , zakat etc.