On Dhu al-Hijjah the 18th AH (March 632 CE), Prophet Muhammad (PBUH & HP), while returning from his last pilgrimage of Hajj named “the Farewell Hajj”, stopped at Ghadir Khumm (a pond) to make an announcement to the pilgrims who had accompanied him in the pilgrimage.

Ghadir Khumm was a place where people (who were about 10 thousand in number) from different lands like Iraq, Syria, and Egypt would part ways. But before they do, Gabriel revealed to the Prophet (PBUH & HP) one of the last verses of Quran. The verse is now called the verse of al-Tabligh (propagation):

يَا أَيُّهَا الرَّسُولُ بَلِّغْ مَا أُنزِلَ إِلَيْكَ مِن رَّبِّكَ وَإِن لَّمْ تَفْعَلْ فَمَا بَلَّغْتَ رِسَالَتَهُ وَاللَّهُ يَعْصِمُكَ مِنَ النَّاسِ إِنَّ اللَّهَ لَا يَهْدِي الْقَوْمَ الْكَافِرِينَ

O Messenger! Communicate that which has been sent down to you from your Lord, and if you do not, you will not have communicated His message (the whole message of Islam), and Allah shall protect you from the people. Indeed Allah does not guide the faithless lot. (The Holy Quran 5:67)

After the verse was revealed to the Prophet (PBUH & HP), he ordered the caravan to stop and ordered those who have passed Ghadir Khumm return and wait until those who had not yet arrived there join them. (1)

After performing the noon prayer, the Prophet (PBUH & HP) made a speech that now is one of the most famous speeches of the Prophet known as Ghadir sermon. Zeid ibn Argham, one of the famous companions of the Messenger (PBUH & HP) said:

“Once, the Messenger of Allah (PBUH & HP) made a speech for us near a pond named Ghadir which is between Mecca and Medina. Firstly, he praised Allah and talked about God and then said: ‘O people! I’m only a human and it is possible that the Apostle of my God (The angel of death) comes to me and I shall accept his invitation (my life ends) and I am leaving you al-Thaqalayn (two great things). The first one is the book of Allah (Quran) in which is guidance and light so follow it and hold fast to it.’ he advised us about the Book and encouraged us to follow it. Then the Prophet (PBUH) said: ‘and (the second one is) my close family.  By Allah, I advise you (to follow) my family, By Allah, I advise you (to follow) my family, By Allah, I advise you (to follow) my family’” (2) 

The Hadith above is known as “al-Thaqalayn”. It is one of the most famous Hadiths of the Prophet (PBUH & HP) which indicates that the most important things which the Prophet has left for all Muslims are Quran and the family of the Prophet. 

Bara’ ibn Azib, another famous companion of the Messenger, narrates the continuation of the Hadith: 

“Then the Prophet raised Ali’s hand (so that all people can see it) and said: ‘don’t you know that I am more deserved to the leadership of the believers than themselves?’. People said: ‘yes, we know’. The Prophet said again: ‘don’t you know that I am more deserved to be the leader of every believer than themselves?’. People said: ‘yes, we know’. Then the Prophet said: ‘anyone whose Mawla is me, then Ali is his Mawla. O God! Be friends with his friends and be enemy of his enemies’. Then, Umar ibn Khattab (the second Caliph) met Ali and told him:

‘Congratulations to you, Congratulations to you, you just got the Mawla of every believer, men or women’” 

Arna’oot, one of the most important religious Sunni researchers admits that this historical record is right and trustable. (3)

What does the word “Mawla” mean?

The word “Mawla” in Arabic language has lots of meanings. Shias and Sunnis disagree on the meaning of the word used in this hadith. 

Sunni viewpoint 

Sunni scholars mostly refuse to believe that the word “Mawla”, used in the Hadith, means “Leader” or “Prior in making decisions for somebody”. They rather suggest it means “friend or helper”. They argue that this word is never used in this meaning (Leader). 

Shiite viewpoint 

Shiites, in reply to Sunni scholars, say that this world have actually been used in this meaning (“the prior”) and some Sunni scholars have admitted that. (4) also, some experts in Arab literature admitted so too like Ghiyath Barghuth, Ajjaj (5), Yahya ibn Ziad al-Farra, Akhfash and so forth. (6)

To prove that the word Mawla in this Hadith means “Leader” and not “friend”, there are many evidences but we mention just one in this text. 

The congratulation of Umar ibn Khattab:

The congratulation of Umar ibn Khattab can be a good evidence to prove that “Mawla” here doesn’t mean “friend”. Because, as we said before, Umar says: “Congratulations to you, you just got the Mawla of every believer, men or women” while Imam Ali was the friend of every believer before the Ghadir event, and it doesn’t make sense that he just got the friend of believers in there. 

Ghazali, one of the most important reflective Sunni scholars in this regard, says:

“(After the sermon) Umar said: ‘Congratulations O Aba al-Hassan (Imam Ali (AS) ), you just got my friend and every believer’s friend’. So this shows submission and satisfaction (that Imam Ali is the successor of the Prophet) but after this event, due to his desire and love for power, he made himself Caliph and leader” (7) 

Revelation of the Ikmal verse

People had not scattered yet, when Gabriel one more time came to the Prophet and revealed another verse to him:

الْيَوْمَ يَئِسَ الَّذِينَ كَفَرُوا مِن دِينِكُمْ فَلَا تَخْشَوْهُمْ وَاخْشَوْنِ الْيَوْمَ أَكْمَلْتُ لَكُمْ دِينَكُمْ وَأَتْمَمْتُ عَلَيْكُمْ نِعْمَتِي وَرَضِيتُ لَكُمُ الْإِسْلَامَ دِينًا

Today the faithless have despaired of your religion. So do not fear them, but fear Me. Today I have perfected your religion for you, and I have completed My blessing upon you, and I have approved Islam as your religion.

The narrators of the Hadith 

The Hadith is that which is frequently narrated by different people and historians that no one can deny its authenticity. 

The family of the Prophet i.e. Imam Ali himself, Lady Fatima, Imam Hassan and Imam Hussain are among the narrators of this Hadith. Also many of the companions of the Messenger narrated this Hadith. Kattani, one of the Sunni scholars, says that about 30 companions of the Prophet narrated this story including: Umar ibn Khattab, Zeid ibn Argham, Abi Hurairah, Sa’d ibn Waghas and etc. (8) 

Due to this fact that this Hadith is so frequently narrated, it is called “Mutavatir”, meaning that this Hadith is undeniable. 

Eid al-Ghadir

Shi'as have always regarded the Day of Ghadir as one of the greatest Eids and this day is known to them as Eid al-Ghadir. Imam Sadiq (AS) says that the Eid al-Ghadir is the greatest Eid of Allah. Its name in skies is “the day of Promise” and in the earth “the day of Covenant”. (9)
Shiites believe that this day was the day that Imam Ali (AS), our first Imam, was officially announced to be the successor of the Prophet (PBUH & HP). So this day is a great holiday for them and fasting in it is so recommended. In this day, Shiites go to the house of Seyyed people -the descendants of Imam Ali and Lady Fatimah- and congratulate them. In return, Seyyed people give them gifts. It is highly recommended to conduct parties in this day and give food to the needy ones.

For more information about Ghadir Khumm, you can read the book al-Ghadir, by Allamah al-Amini (Arabic). 

Resources 

1. At-Tafsir, al-Ayyashi, vol.1, Pg.332 
2. Sahih al-Muslim, vol.4, Pg.1873
3. Musnad ibn Hanbal, published by ar-Risalah, vol.30, Pg.430
4. Sharh al-Maqasid, al-Taftazani, vol.5, Pg.273
5. Al-Shfi, Sharif al-Murtaza, vol.2,  Pg.270
6. At-Tafsir al-Kabir, Fakhr ad-Din ar-Razi, vol.29, Pg.227
7. Sir al-A’lamin, al-Ghazali, vol.1, Pg.18
8. Nazm al-Mutanathir, al-Kattani, vol.1, Pg.194
9. Vasa’il ash-Shiah, Sheik Hurr al-A’meli, vol.5, Pg.224
    

Life is a journey full of twists and turns. Without a guide in this deceptive path, one can become lost, forfeiting something that cannot be regained - the precious gift of redemption. That is why Islam emphasizes the need for Muslims to never be without a leader. Prophet Mohammad (PBUH&HP) is the best example of a Muslim within Islam.

There has certainly been for you in the Messenger of Allah an excellent pattern for anyone whose hope is in Allah and the Last Day and [who] remembers Allah often. (The Holy Quran 33:21)

O you who have faith! Obey Allah and His Apostle, and do not turn away from him while you hear [him]. (The Holy Quran 8:20)

These Quranic verses firmly establish that no one surpasses Prophet (PBUH&HP) as the ideal role model, guiding us to emulate his actions and lifestyle for our salvation. When we follow someone as a model in our life, we inherently respect his beliefs and ideas. 

From this, we deduce that if our model is devoted to Islam, religion, and the path of Allah's pleasure, we will also try to align ourselves with that path and potentially attain spiritual ascension. Our model here is not an ordinary person but our dear Prophet. Therefore, there is no disputing the goodwill of this revered figure. An important thing that we must learn from the Prophet (PBUH&HP) as the supreme model for Muslims is to know whom to love and whom to dislike.

The question is: how does understanding Prophet’s feelings towards individuals would help us? 
The answer lies in this: “By following the Prophet as an example, we can accurately discern these people, subsequently progressing toward Allah’s satisfaction and eternal happiness.” 

Two figures whom the Prophet constantly favored were Imam Hassan and Imam Hussein (as). Imam Hussein (AS) was born on the third of Sha'ban in the fourth year of AH.

Since the great Prophet passing in the tenth year of AH, Imam Hassan and Imam Hussein (AS) spent their childhood with their dear grandfather.

Before delving further, let us know more about our third Imam. Imam Hussein (as) is also called Aba-Abdillah and Sayyid al-Shuhada among the Shias. He is the third Imam for the Shias, martyred in the course of Ashura. He is the second child of Imam Ali (AS) and Fatemeh Zahra (AS), and the grandson of Prophet Mohammad (PBUH&HP). Following his brother Imam Hassan’s (AS) leadership, he took charge of leading the Shias for ten years. Both Shia and Sunni historical records confirm that the Prophet of Islam (PBUH&HP) announced his martyrdom at his birth and chose the name "Hussein" for him. (1)

The Prophet held deep affection for Imam Hassan and Imam Hussein and recommended everyone to love them. Imam Hussein (AS) is one of the of Prophet’s Ahl al-Bayt and also one of the recipients of the verse of purification*.

Numerous narrations from Prophet Mohammad (PBUH&HP) extol Imam Hussain’s virtue. A famous narration quotes the Prophet (PBUH&HP) on Imam Hussain (AS): “Hussain is from me and I am from Hussain. Allah loves who loves Hussain.” (2)

Through this narration, the Holy Prophet (PBUH&HP) show other Muslims the sacred position of Imam Hussein (PBUH) and imparts the exceptional stature of this lineage. In an era where falsehood and hypocrisy infiltrate the Muslim community, this saying compels believers to rid themselves of hypocrisy and misguidance. 

Regrettably, despite its resonance, this profound message did not deter the brutal martyrdom of Sayyid al-Shuhada (PBUH), which transpired in the Karbala before thousands of seemingly Muslim individuals.

The Prophet’s (PBUH&HP) adoration for Imam Hussein (AS) served a dual purpose: it conveyed not only his love for his grandson, but also aimed to engender affection towards Imam Hussein as the Imam of the Ummah, rallying people to follow him. Therefore, the Holy Prophet of Islam consistently introduced the Imam Ali, Fatima Zahra, Imam Hassan and Imam Hussein (AS) as his family and Ahl al-Bayt. He equated them with the Quran on numerous occasions,  underscoring the necessity for Muslims to accept their leadership and guidance for spiritual elevation. The Prophet also said this in the hadith of the thaqalayn: 

"Indeed, I am leaving two things among you, to which if you hold yourself, you will never astray: the book of Allah –who is almighty and great- and my Ahl al-Bayt (household), my 'itra (family). O people hear! And I have announced to you that indeed you will enter my presence and I will ask you about what you did to the thaqalayn (two weighty things) and the thaqalayn are the book of Allah and my Ahl al-Bayt."(3)

Conclusion: 

These narrations illuminate Imam Hussein’s (AS) lofty status in the the Prophet’s (PBUH&HP)eyes and the Prophet’s responses to him serves as a guide. Not only are Muslims, as followers of the Holy Prophet, must praise and love Imam Hussein, but we must also adopt his behavior, thoughts, and ethics, and follow his path in our lives. Furthermore, the Prophet's interactions with Imam Hussein underscore that those who harbor hostility or animosity towards him today are not true Muslims. This group should not be regarded as part  of the Prophet’s (PBUH&HP) religion.

References:

1.  Al‑Irshad (2nd Volume - page 130)
2.  Sunan al-Termizi (6th volume – number 3775)
3.  Al-Kafi (1st Volume – page 452)

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*The Verse of Purification is the 33rd verse of Al-Aḥzāb in the Quran (33:33). The verse has special importance for Shia Muslims due to giving information about Ahl al-Bayt of Prophet Muhammad (PBUH&HP). Shias reportedly believe it to designate the "Ahl al-Bayt" being infallible.