Deliver what bas been revealed to you from your Lord...
Deliver what bas been revealed to you from your Lord; and if you do it not, then you have not delivered His message, and Allah will protect you from the people; surely Allah will not guide the unbelieving people.” [Surah al-Ma`idah 5:67] Immediately, the Holy Prophet (S) ordered the caravans to halt at Ghadir Khumm and delivered the Lord’s message. He raised `Ali to the minbarlike height made of saddles, took him up from the arm and declared him as the next leader.
He also ordered to establish a tent in which `Ali would sit and Muslims would congratulate him on this leading position. The attendant Muslims offered congratulations and paid him homage. On that occasion, Almighty Allah revealed, “This day have I perfected for you your religion and completed My favor on you and chosen for you Islam as a religion.” [Surah al-Ma`idah 5:3] That was on the eighteenth of Dhu’l-Hijjah.
Before and after his arrival at al-Madinah, people of Quraysh and the hypocrites started their activities against the Holy Prophet (S). All of their plots were foiled by the Lord Who protected His Messenger against any movement of mutiny or apostasy during his lifetime. Various means were used for this purpose. One of these was the heavenly chastisement inflicted upon those who objected and protested against him.
Jabir ibn al-Nadr ibn al-Harith al-`Abdari whose father was the chief of the [tribe of] `Abd al-Dar and the commander of the polytheists’ army against Muslims during the Battle of Badr was one of those objectors: Abu-`Ubayd al-Harawi, in Gharib al-Qur’an, records the following: After the Holy Prophet (S)’s conveyance of the Lord’s commission in Ghadir Khumm had been widely known, al-Harith ibn al-Nu`man al-Fihri (or Jabir ibn al-Nadr ibn al-Harith ibn Kildah al-`Abdari, according to Abu-`Ubayd’s report) came to the Holy Prophet (S) and said, “O Muhammad!
You have ordered us, on behalf of Allah, to declare that there is no god but Allah and that Muhammad being the Messenger of Allah, perform the prayers, observe fasting in the month of Ramadan, undertake the [obligatory] Hajj and defray the zakat; and we have admitted.