Racism and ethnocentrism are closely linked to the sense of superiority that lies within every human being. This issue has a long history - as long as human life, and is still an ongoing behavior that causes serious problems among human beings.

Racism is an important issue that Islam has considered; the issue whose history dates back to nations existed long before the birth of Prophet Muhammad (PBUH&HP). This unequal treatment was so weaved into people’s lives which they didn’t even realized its vile nature. Prophet Muhammad (PBUH&HP), also, lived in a society where racism was very common. The situation became even harder when people started to follow the religion of Prophet Muhammad (PBUH&HP). That was when racism out of tribal prejudice was extended to segregation based on religion, and many people who followed Prophet Muhammad (PBUH&HP) were driven from their homes or hometowns. 

The specific conditions of the era in which Prophet Muhammad (PBUH&HP) lived, as well as the deep roots of this wrong attitude in the history of humankind, were the main reasons why Allah (SWT) makes many recommendations about racism in the Quran. The Prophet of Islam (PBUH&HP), also, worked really hard to clear the minds of people from tribal, religious, and any other types of racism.

What does the Quran and Prophet Muhammad (PBUH&HP) say about Racism?

During the Arab ignorance, privileges such as lineage, race, wealth, number of children, and affiliation with a powerful tribe were considered the criteria of superiority over others. The verses of the Quran indicate that the number of children and folks were so important to them that in some arguments they even went to a cemetery and started to count the number of their dead ones:

 “Rivalry [and vainglory] distracted you until you visited [even] the graves.” (102: 1-2) 

It should have been hard for people of that mindset to accept that their lineage, children, tribe and wealth is of no importance in the eyes of Prophet Muhammad (PBUH&HP). According to an account, he said, “All the people, from the past or at present, are as equal as a comb’s teeth; therefore neither Arabs are superior to non-Arabs, nor white people to blacks. You are only distinguished by your piety and righteousness” [1]. 

However, although the Quran was revealed in such an environment that was limited in various ways and had a limited connection with the world outside the island, and the issue of ethnicity, race, and tribal life prevailed in all its aspects, it did not take on such a color at all. Allah addresses people in the Quran using the following phrases: "O children of Adam," "O people," "O you who believe," or "O you who have faith." The Quran removed racial privileges in that racist environment, and with the beautiful logic of "you are all children of man and were created from one parent," Allah declared them all brothers and sisters belonging to the same family:

“O mankind! Indeed, We created you from a male and a female and made you nations and tribes that you may identify yourselves with one another. Indeed the noblest of you in the sight of Allah is the most God wary among you. Indeed Allah is all-knowing, all aware.” (49:13)

As the verse above implies, One’s character and status are only measured by the level of submission to Allah and following His commands, not social or financial conditions. 

Religious Discrimination 

Apart from racism based on lineage, race, wealth, etc. people before and at the time of Prophet Muhammad (PBUH&HP) believed that religious beliefs gave them superiority over others. 

Based on that belief, people of different faiths were always conflicting with each other, instead of having sound arguments about different issues. Therefore, religious discriminations had been severely condemned by Islam, emphasizing that belonging to the followers of religion does not make people good or bad. But, it is their actions and their level of obedience toward Allah that give them superiority: 

“The Jews say, ‘The Christians stand on nothing,’ and the Christians say, ‘The Jews stand on nothing,’ though they follow the [same] Book. So said those who had no knowledge, [words] similar to what they say. Allah will judge between them on the Day of Resurrection concerning that about which they used to differ.” (2: 113)

The Quran on sexism 

The issue of fairness and justice among human beings is so important in Islam that the Quran has taken care of all different aspects in which people may act unjustly toward each other. Apart from racial issues that have been ongoing for ages, the issue of undermining and suppressing women in different domestic and social aspects, and depriving them of their rights had been a challenging issue in most parts of the world. 
The Quran condemns this segregation and states that men and women are equal in the eyes of Allah: 

“Whoever acts righteously, [whether] male or female, should he be faithful, We shall revive him with a good life and pay them their reward by the best of what they used to do.” (16:97)

Also, the necessity of observing women’s rights had been emphasized in many narrations from Prophet Muhammad (PBUH&HP) and his progeny. Imam Ali (AS), says in an account, “Women are Allah’s trusts upon you, do not hurt them, and do not put pressure on them” [2]. Therefore, men should be careful with their manners in treating women whether in family or in society. 

To conclude, the only thing that gives superiority to people is their piety and faith. Looking at the issue like this makes people closer to each other and all differences in color, race, ethnicity, shape, wealth, etc. create no distance between people. People gather around based on their spiritual interests and try not to judge each other, since the only one who is aware of the most faithful is Allah (SWT): 
“… And be wary of Allah. Indeed Allah knows best what is in the hearts.” (5: 7).

References:

1. Al-Shaykh Al-Mufid, Al-Ikhtisas, p.341.
2. Muhaddith Nuri ,Mustadrak al-Wasail, vol.2, p.551.

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