Eid al-Ghadir is a revival of spirituality alongside material aspects. It is the day of the appointment of Ali (a) as the successor to the Prophet (s) by divine commandment through the angel Gabriel. Therefore, this Eid is considered one of the most important and greatest celebrations among Muslims. In this regard, one of the companions of the Imams (a) asked Imam al-Sadiq (a), "Do Muslims have any other Eid besides Friday, Eid al-Adha, and Eid al-Fitr?"
He said, "Yes, the greatest of them is the sacred one."
I said, "And which Eid have you made as your ransom?"
He said, "The day on which the Prophet (s) appointed Ali (a) as the Commander of the Faithful and said, 'Whoever I am his master, Ali is his master.'"
I said, "And which day is it?"
He said, "What are you going to do on that day? The year revolves, but it is the eighteenth day of Dhu al-Hijjah."
So, I said, "What should we do on that day?"
He said, "Remember Allah (glorified be His mention) on that day through fasting and worship and remember Muhammad and the family of Muhammad. For the Prophet (s) advised Ali (a) to designate that day as a celebration, and the Prophets used to do the same. They would advise their successors to observe it as a celebration."
So, it is upon the Muslims today to make this day a motivation for them to do good deeds and righteousness, to turn to Allah in every action of theirs, and to stand against the oppressors and enemies of the religion, so that they may draw closer to the Exalted and Almighty.