Undoubtedly, the day of Ghadir is the day when the religion of Allah was perfected. The role of the prophet in delivering the religion of Allah was accomplished and thereafter the role of the Imams, to spread and protect it, began.  

Under the scorching sun, in the valley of Ghadir, the Holy Prophet (peace be upon him & his progeny) summoned everyone who had accompanied him on the pilgrimage to Haj and instructed them to make a stage wherein everyone could see him. Ghadir was a place where people coming from different parts of the Islamic nation parted ways, hence it was an important junction at the time. 

When the stage was set, the Prophet recited a sermon and said, ‘ O people! This is the last stand I make in such a situation; so, listen and obey, and submit to the Command of Allah, your Lord, for Allah, the Exalted and the Sublime One, is your Master and Lord, then after Him is His Messenger and Prophet who is now addressing you, then after Him 'Ali is your Master and Imam according to the Command of Allah, your Lord, then the imams from among my progeny, his offspring, till the Day you meet Allah and His Messenger.’

Thereafter, a tent was made and everyone, even the females pledged allegiance to the Imam (peace be upon him).

Therefore, this day is a special day as Allah completed his favors upon his creation by the appointment of a successor to His prophet. Indeed, it is only Allah who knows the one worthy of leading an entire Ummah.

On this greatest day, we ask Allah to instill in us and our progenies the teachings of Ghadir and help us to be amongst the propagators and helpers of the Imam of our time (may Allah hasten his reappearance)