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
    

After Imam Ali (AS) was martyred, Imam Hassan (AS) took over as his successor who like his father fought against Mu’aviah but he couldn’t defeat him because his army was not sufficiently loyal. His reliable followers were inadequate and he feared that they could be killed in the battle. Thus, Imam Hassan (AS) made a peace treaty with Mu’aviah, under the duress against his own will. 

Mu’aviah became the Caliph under specific circumstances. For instance, he wasn’t allowed to choose the next Caliph and his son (Yazid) couldn’t be his successor. On the other hand, when Mu’aviah died, Imam Hussain (AS) was opposed to and fought against Yazid and he and his followers were brutally martyred. Both Imam Hassan (AS) and Imam Hussain (AS) had few collaborators/ associates/ helpers; however, this did not stop him from protesting against Yazid and his tyranny. 

One of the most controversial questions about Imam Hussain (AS) is that why he did not make peace with Yazid just like his bother did with Mu’aviah? 

The Wrong Belief

It is worth noting that it would be so irrational to think that Imam Hussain (AS) had a different disposition from Imam Hassan (AS), for example one was more of a diplomat while the other was more of a fighter. In fact the objective conditions at the times of two Imams were rather different hence, their approach apparently differed. 

1.    Mu’aviah was willing to make peace with Imam Hassan (AS) but Yazid wasn’t like his father. Mu’aviah did not want to fight against either Imam Hassan (AS) or Imam Hussain (AS) and they were not prepared to do so. Once the governor of Medina wrote to Mu’aviah that Hussain (AS) does not want to take over the kingdom for now but he may do in the future. Mu’avia wrote to the ruler:
Leave Hussain (AS) and do not bother him because we don’t want to conflict with him while he is in peace with us (1)

On the other hand, when Yazid became the Caliph, he ordered the  governor of Medina to make Imam Hussain (AS) to either obtain the oath of loyalty (to the Caliphate of Yazid) or failing that, kill Imam Hussain (AS), cut off his head and send it to Yazid.

2.    In public Mu’aviah was, at least superficially, a pious person who would not commit sins or harm innocent people. Sometimes even the followers of Imam Ali (AS) had doubts about the impiety of Mu’aviah. While Yazid had no reservations, he would commit sins in public including drinking wine, playing with dogs and monkeys and etc. As in  this regard Imam Hussain (AS) said:
Yazid is an alcoholic person and kills innocent people and does sins in public, so a person like me wouldn’t accept a person like him as their king (2)

3.    Mu’aviah was a very powerful king with strong army but Yazid was not as clever and strong.

4.    The loyalty of many of Imam Hassan’s (AS) followers was questionable.   Some abandoned him and some others tried to kill him or even surrender him to Mu’aviah. But the companions of Imam Hussain (AS), as he himself said, were of a better and more loyal caliber. (3)

5.    Mu’aviah was among the companions of the Prophet (PBUH) which earned him the respect of Muslims in general whereas Yazid was not a companion of the Prophet (PBUH) was so important to Muslims in that time and people would respect him so much. But Yazid wasn’t a companion of the Prophet. 

6.     Mu’aviah’s sister (Um Habibah) was the Prophet’s wife. Since the prophet’s wives are called ‘’the mothers of the believers ‘’; therefore, Mu’aviah was called “the uncle of the believers”. Yazid, however, did not have such status.

7.    Although he did not meet any of his commitments that he had already made, Mu’aviah could say that he is legally the caliph because of the peace agreement between him and Imam Hassan (AS) because Yazid could not claim such legitimately. 

Imam Hussain (AS) and respect to the Peace

Some people think that Imam Hussain (AS) didn’t agree with his brother in making peace with Mu’aviah however because of his respect for his brother, he observed the peace treaty and did not oppose Muaviah. However, this view about Imam Hussain is not right.

If we assume/Supposing that Imam Hussain (AS) did not actually agree with his senior brother, he could fight against Mu’aviah; because, the latter broke his agreement that he had made with Imam Hassan (AS), when he made his son, Yazid, his successor and Imam Hussain (AS) had no agreement with Muaviah however the circumstances of Imam Hussain were unsuitable for an uprising against Muaviah.

References 

1.  Bihar al-anvar, Majlesi, vol.44, pg.212
2.  Maghtal al-Hussain (AS), Abd ar-Razzaq al-Muqarram, pg.129
3. Musnad al-Imam ash-Shahid, al-Atarodi, vol.2, pg.4