In Islam, there are some ceremonies and occasions which are held all around the world among Muslims. They all have religious backgrounds and are mostly referred to in the holy Quran. Muslim nations have been commemorating them in the course of history. Here we are going to have a glance at the most significant Islamic occasions based on the Lunar Calendar.

6 Major  Islamic Occasions 

1.10th of Muharram: Martyrdom of Imam Hussain (AS)

The month of Muharram is the first month of the year in the lunar calendar. On the tenth day of this month, Hussain Ibn Ali (AS), the grandson of Prophet Muhammad (PBUH&HP), and his companions were brutally martyred, and their women and children were taken captive by the caliph of the time, Yazid ibn. Muawyah. Their story has been the source of inspiration for many new converts. 

2. 20th of Safar: The Day of Arbaeen

Arbaeen is the Arabic word for forty, and it marks the 20th of Safar, the fortieth day after Imam Hussain's (AS) martyrdom on the day of Ashura, who was martyred in the event of Karbala along with his companions in the cruelest and most inhumane way possible. 

According to some historical accounts [2], some of the members of Imam Hussain's (AS) family after being released from the bondage of Yazid's forces returned to Karbala from Sham (today's Damascus) to visit Imam Hussain's (AS) grave. Also, some believe that Imam Hussain's (AS) head, which was taken to Sham by Yazid's army was brought back to Karbala on this day and buried with his body [3] & [4]. 

Every year, a few days before this day, a vast number of people from all over the world, Muslims or even non-Muslims, gather in Iraq to take part in a symbolic walk, to revive the teachings of Imam Hussain (AS) and commemorate his sacrifice in the way of Allah and humanity. 

3. 17th of Rabi al-Avval: Prophet Muhammad's (PBUH&HP) Birthday

There is a disagreement concerning the exact date of Prophet Muhammad's (PBUH&HP) birthday. Some believe it occurred on the 12th of Rabi al-Avval, while others consider it to be on the 17th of Rabi al-Avval, the third month in the Islamic calendar. Prophet Muhammad (PBUH&HP) was born in Mecca. All Muslims around the world celebrate his birthday and regard it as one of the important Islamic occasions. On this day, Muslims feed the needy, pray and recite the Quran, commemorate Prophet Muhammad (PBUH&HP), and his challenges to deliver the messages of Allah to human beings.

4. 1st of Shawwal: Eid al-Fitr

The first day of the month of Shawwal, the tenth month of the Islamic calendar, is called Eid al-Fitr. After fasting for one month, during the month of Ramadan, remembering, worshipping Allah and trying to do fewer sins beside not eating and drinking from before the Call for Fajr prayer to after the Call for Magrib prayer, Muslims celebrate the first day of the month of Shawwal, for their success in submitting to Allah's command. They perform the Eid prayer first; then, they hold a feast inviting their loved ones, wear their best clothes, and visit their friends and family. The culture of feasting might be different in different Islamic communities, but one thing is for sure; no one is allowed to fast on this exceptional day. Allah also obliges Muslims to share their blessings and happiness with the needy with the money they donate to them. 

5. 10th of Dhu'l-Hijjah: Eid al-Adha

Eid al-Adha is one of the most significant Islamic occasions. Some of the most important events of this Abrahamic religion happened on this day. On this Eid, similar to Eid al-Fitr, Muslims are not allowed to fast. The first is the sacrifice of Ishmael by his father, Abraham, for the sake of Allah. When Abraham and his son both surrendered, and he was ready to behead his son, Allah sent a ram and asked Abraham to kill that instead.

"So when they had both surrendered [to Allah's will], and he had laid him down on his forehead, We called out to him, 'O Abraham! You have indeed fulfilled your vision! Thus indeed do We reward the virtuous! This was indeed a manifest test. Then We ransomed him with a great sacrifice, and left for him a good name in posterity." (37: 103-108)

This day is also the last day of Hajj rituals, in which Muslims shall sacrifice an animal to feed the needy Muslims. On this day, those who attended Hajj have performed all their Hajj rituals, and with the great assistance of Allah, all their sins are wiped away, and Allah accepts their good deeds and repentance.

Many Muslims celebrate this day. They sacrifice an animal to feed the needy, even if they have not attended Hajj. If they do not have enough money to buy a sheep, they do other things and feed the destitute in different ways. This sacrifice is an expression of generosity and obedience to the commands of Allah. This Eid also reminds humankind of the characteristics, such as envy, rage, dishonesty, etc., they have to symbolically sacrifice in themselves to become the better version of themselves and be worthy of being Allah's best creation. 

5. 18th of Dhu'l-Hijjah: Eid al-Ghadir

This Islamic occasion was a day in the last Hajj pilgrimage (Hajjat al-Vida'a) of Prophet Muhammad (PBUH&HP). When he was going back to Medina with all his companions and other pilgrims, he gathered everyone around a place called Ghadir and announced these words in which he appointed Imam Ali b. Abi Talib (AS) as his caliph and the Imam after himself following a direct order from Allah [i]:

"Whomsoever, I am his leader (Mawla), Ali (AS) is also his leader (Mawla). O' Allah! Love those who love him (Ali (AS)) and oppose those who oppose him" [1]

This is another important day in the Muslim calendar. On this day, Muslims can fast and again feed the needy, as an essential part of Islamic culture. 

These are the most significant and most celebrated Islamic occasions. As one can see, feeding others and praying to Allah are the essential things a Muslim should do to celebrate a feast, which reveals the importance of caring for others in Islam that results from the devotion to Allah.  

Notes: 
[i] Verse 67th of Surah al-Maedah known as Al-Tabligh Verse, and the third verse of the same chapter known as Al-Ikmal Verse. 

References:

1.  Ibn Athīr, Usd al-ghāba, vol. 3, p. 605; Kulaynī, al-Kāfī, vol. 1, p. 295; Balādhurī, Ansāb al-ashrāf, vol. 2, p. 110-111;
2.  Ibn Tawus, 'Ali b. Musa, Al-Luhuf 'ala qatla l-tufuf, Uswi, Qom, 1414 AH.
3.  Al-Biruni, Abu Rayhan, The Remaining Signs of Past Centuries, p.331.
4. Qazi al-Tabataii, Muhammad Ali, A Research on the first Arba'een of the Leader of Martyrs (Imam Hussain (AS)), vol.3, p.304.
    

Imam Ridha (AS) is the eighth Shiite Imam. His original name was Ali, and his father’s name was Musa (AS). He was also known the Ra’uf Imam, which means a kind-hearted person. He was born on Dhu al-Qa’da 11th 148 H (765 AC).

Imam Ridha (AS) was the successor of his father, Imam Musa al-Kazim (AS). After Imam Kazim (AS), the Shia community faced several problems:

Firstly, a new deviated branch of the Shias emerged, called “Waghifiah”. Waghfiah believed that Imam Musa al-Kazim (AS) hadn’t died and he was still alive. They said that Imam Kazim (AS) was the promised Mahdi (AS) in Occultation and he would return one day. This rumor spread among the Shias, and many of them struggled with this test, denying the Imamate of Imam Ridha (AS).

Secondly, the situation worsened due to the belief that Imam Ridha (AS) had no living son which implied he had no successor. Those who denied the Imamate of Imam Ridha (AS) considered this as a sign that he was not a legitimate Imam. This was one of the most dangerous tests the Shias faced. 

Thirdly, during Imam Ridha (AS) time, the Shia population had significantly increased, and many Shias were engaging in conflicts with the contemporary Abbasid Dynasty government. Abbasid dynasty was consistently hostile towards the Shias, subjecting them to severe oppression, especially during time of Harun ar-Rashid, one of the Abbasid kings in the time of Imam Ridha (AS). To ensure the survival of the Abbasid dynasty, Ma’mun, the successor of Harun, attempted to gain favor with the Shias by falsely declaring Imam Ridha (AS) as his successor. This led many people to believe that Imam Ridha (AS) had a good relationship with the cruel Abbasid dynasty, causing them to deny his Imamate.

Imam Ridha (AS) successfully resolved all these three problems during his time as Imam. 

The Problem of Waghifiah 

The beliefs of the Waghifiah were actually against the hadiths of Prophet Muhammad (PBUH & HP).

They believed that Imam Kazim (AS) was the last Shiite Imam and the promised Mahdi (AS).

However, Prophet Muhammad (PBUH & HP) had foretold that there would be twelve successors (Imams) after him:

Indeed, this religion will not end until twelve successors [of me] rise among the people. (1)

Based on this and similar hadiths, Imam Ridha (AS) refuted the beliefs of the Waghifiah. 

the Son of Imam Ridha (AS)

After a while, Imam Jawad (AS), the son of Imam Ridha (AS) was born. Now people could see that Imam Ridha (AS) have a legitimate successor, and their doubts were unfounded. About Imam Javad (AS), Imam Ridha (AS) said:

No more blessed child than this boy has been born for the Shias. (2) 

The birth of Imam Javad (AS) served as a proof of  Imam Ridha’s (AS) Imamate. 

The secession of Ma’mun

Ma’muns’ policy concerning Imam Ridha (AS) aimed to deceive the Shias, and it did deceive some of them. However, Imam Ridha (AS) had his own strategy. Initially, he refused Ma’mun’s proposal to become his successor. Still, Ma’mun forced Imam Ridha (AS) to accept it, threatening to kill him otherwise.(3) Therefore, Imam Ridha (AS) accepted under conditions. Imam Ridha (AS) said:

I accept your proposal under the condition that I can’t command or prohibit anyone, I won’t be the Judge, I won’t appoint anyone to be a ruler or to depose one. I won’t change anything. (4)

Ma’mun accepted these conditions, but he didn’t realize that this demonstrated would Imam Ridha’s (AS) disagreement with his plan. By making this condition, accepting Ma’mun’s proposal was no different from rejecting it. After a while, Ma’mun understood that he couldn’t use Imam Ridha (AS) to deceive the Shias, so he decided to kill Imam Ridha (AS), and he did. 

Imam Ridha (AS) was poisoned by Ma’mun on Safar 30th, 203 H (818 AC).

Resources

1. Sahih al-Muslim, Muslim an-Neishaburi, vol.3, pg.1452
2. Al-Kafi, Sheikh Koleini, vol.1, pg.321
3.  I’lal ash-Shara’I, Sheikh Saduq, pg.238
4.  I’lam al-Vara, Sheikh Tabarsi, vol.2, pg.72