Imam Jawad (AS) is the ninth Shiite Imam. His father is Imam Reza (AS), and his mother’s name is  Sabikah. His original name is “Muhammad,” but his epithet is “Jawad,” meaning “a very generous person.” He was born on 195 H (810 AC) in Medina. (1)

Generally, Shiite Imams carried prestige among their tribe and were respected by everyone. Many Shias believed that Imams were merely knowledgeable people who gained their knowledge only from their ancestors and they were not extraordinary. However, the imamate of Imam Jawad (AS) made all the Shias think differently and change their minds. He was only eight years old, when his father, Imam Reza (AS), was martyred. According to hadiths, the earth cannot be without an Imam. Accordingly, Imam Reza (AS) said:
The earth cannot be without any of us, Imams, whether he is known by the people or hidden from them. (2)

Shias didn’t know who would be their leader after Imam Reza (AS). But, he introduced Imam Jawad (AS) as his successor (3) and showed the Shias that “Imam” was not an ordinary person and he could be the leader of the whole Shias despite being young. 

Knowledge is a sign of imamate 

The hadiths suggest various signs for Imams so that we can differentiate between the truly chosen Imams by Allah and impostors. One of the most significant signs is that he is the most knowledgeable person of his time. 

Prophet Muhammad (PBUH & HP) said:
Do not try to teach something to Ahlul Bayt because they are far more knowledgeable than you. (4)
Regarding this, Imam Sadiq (AS) acknowledged:
Indeed Ali (AS) was a knowledgeable person whose knowledge will be passed to his successors and no knowledgeable person (an Imam) dies except to leave their knowledge to someone else. (5)
He also said:
The successor of an Imam attains the knowledge of the previous Imam in the last moment of his life. (6)

The debates of Imam Javad (AS) with religious scholars

Ma’mun was one of the Abbasid Caliphs who lived during the same period as Imam Reza (AS) and Imam Jawad (AS). During his caliphate, the Shia population increased dramatically which intimidated him. Due to this fact, he lied that Imam Reza (AS) was his successor and led people to believe that he was not an enemy of Shiite Imams. But at last, he killed Imam Reza (AS). After Imam Reza (AS), Imam Jawad (AS) was his most important enemy. He made Imam Jawad (AS) marry his daughter so that he could deceive people longer. 

Many of the Abbasid royalties were against Ma’mun’s decision, as they believed that the boy was too young and he wasn’t a knowledgeable person. Ma’mun proposed that they should test the knowledge of Imam Javad (AS), in order to show everyone how extraordinary he is. Imam Javad (AS) was only nine years old at that time. 

One of the most knowledgeable religious scholars in those times, Yahya ibn Aktham, volunteered to have a discussion and debate with Imam Javad (AS). 
During the discussion, Yahya ibn Aktham asked Imam Javad (AS) about a person who has killed an animal while making Hajj; what should he do? (During the Hajj ceremony, it is forbidden for the pilgrims to kill any creature).
Imam Jawad (AS) said that it depends: Did he kill it in Mecca or outside of it? Did he know about this law or not? Has he done it intentionally or unintentionally? Was he free or was he a slave? Was it his first time? Was it a bird or something else? Was it a small animal or a big one? Is he ashamed of what he did or not? Did he do it at night or during the day? Was it Umrah (a special type of Hajj) or regular Hajj? 
Yahya was so surprised that he couldn’t answer the twelve questions of Imam Jawad (AS), but instead, Imam Javad (AS) answered them one by one and explained the rules to everyone. 
Ma’mun told people that “Now do you see what I was telling you?” (7)
During another session, Yahya asked Imam Jawad (AS) about a hadith from the Prophet (PBUH & HP) that Sunni narrators had recorded. The hadith said “Once Gabriel came to the Prophet (PBUH & HP) and told him ‘O Muhammad! Allah told you to inform Abu-Bakr that I am satisfied with him. Is he satisfied as well?” Yahya questioned Imam Javad (AS) about the authenticity of this hadith.
Imam Jawad (AS) said, “I do not deny the privileges of Abu-Bakr … but this hadith is contrary to the verses of the Quran.” Imam Javad (AS) stated he wouldn’t deny the privileges of Abu-Bakr because he was surrounded by Sunnis and it was so dangerous for him to speak out against Abu-Bakr.
Then he said, “The holy Quran says 
‘Surely We have created man, and We know the promptings of his heart, and We are nearer to him than even his jugular vein.’ (50:16) 
Then why should Allah ask Abu-Bakr whether he is satisfied with him or not while Allah already knows it?”
Yahya referred to another hadith that claims Abu-Bakr and Umar on the earth are like Gabriel and Michael in the skies. 
Imam Javad (AS) said “This hadith cannot be accepted as well, because Gabriel and Michael never worshiped anyone except Allah, while Abu-Bakr and Umar spent most of their lives as polytheists and worshippers of idols.” 
Yahya added that Abu-Bakr and Umar are the lords of the elderly in Paradise.
Imam Javad (AS) stated that it is impossible as people in Paradise are all young not old. Umayyad dynasty made this fake hadith because they didn’t like the authentic one narrated by the Prophet (PBUH & HP) that reads, “Hassan (AS) and Hussain (AS) are the lords of young people in Paradise.” (8)
Yahya said it also has been narrated that Umar is the one who illuminates Paradise.
Imam Javad (AS) responded that it is also impossible. Do you think that Paradise is not illuminated by the Angles and Prophets like Adam (AS) and Muhammad (PBUH & HP) but rather by Umar?!
Yahya said it has been claimed that the angels talk with the tongue of Umar.
Imam Jawad (AS) said that he does not deny the privileges of Umar. However, Abu-Bakr was better than Umar as he said, “I have a Satan that sometimes tempts me, so if you see me deviating, stop me.” 
Yahya asked many other questions about Abu-Bakr and Umar, and Imam Javad (AS) answered them all. (9)   
Not only Imam Javad (AS) did not fail to answer the questions, but also, he posed more questions that even the most knowledgeable scholars felt incapable of disputing with Imam Javad (AS). These debates happened when Imam Javad (AS) was only 8 or 9 years old. 
As it might be apparent, Shiite Imams were extraordinarily knowledgeable, and their knowledge was given to them by God not by learning in classes and the like. They were the most knowledgeable individuals in their era regardless of their age.

Resources

1.  I’lam al-Vara, Sheikh at-Tabarsi, vol.2, pg.91
2.   Kamal ad-Din, Sheikh Saduq, vol.1, pg.202
3.  Al-Kafi, Sheikh Koleini, vol.1, pg.320
4. Mu’jam al-Kabir, at-Tabarani, vol.5, pg.166
5.  Al-Kafi, Sheikh Koleini, vol.1, pg.221
6.  Al-Kafi, Sheikh Koleini, vol.1, pg.275
7.  Al-Ih’tijaj, at-Tabarsi, vol.2, pg.444
8. Sunan al-Kubra, Nasa’i, vol.7, pg.460
9. Al-Ih’tijaj, at-Tabarsi, vol.2, pg.446-448
    

Prophet Muhammad (PBUH&HP) was the last messenger of Allah Almighty sent to human beings to guide them towards a more prosperous and meaningful life: "O Prophet! Indeed, We have sent you as a witness, as a bearer of good news and as a warner. and as a summoner to Allah by His permission, and as a radiant lamp." (33:45-46). 

You might be interested to know more details on his delegation (be' tha). So, follow us to find out more.

1. How did Prophet Muhammad (PBUH&HP) Receive his First Revelation?

Prophet Muhammad (PBUH&HP) was born into the tribe of Quraysh, one of the prominent tribes of Mecca. He was known as an honest and faithful man such that he was called Al-Amin [i], meaning trustee. 
He used to spend some hours alone out of town in Hira cave to worship, contemplate and reflect the state of people of that time and the aspects of creation. It was during one of these occasions that he received the divine message of prophethood. He was nearly 40 at that time. It was Rajab the 27th on 610 CE that the Archangel Gabriel (Jibreel) appeared before him and said: "Read." Muhammad (PBUH&HP) replied: "I am not able to read." This was repeated two more times. Then, the angel Gabriel recited the first verses of the Quran:

"Recite in the name of your Lord who created -
Created man from a clinging substance. 
Recite, and your Lord is the Most Generous –
Who taught by the pen -
Taught man that which he knew not." (96:1-5)

And, his mission started there.

2. How Was the Condition of the People in that Era?

According to Imam Ali (AS), Allah Almighty sent Prophet Muhammad (PBUH&HP) as a warner (against vice) for all the worlds and a trustee of His revelation. That was while the people of his time were following the worst religion. They resided among rough stones and venomous serpents, drank dirty water and ate filthy food, shed each other's blood, and did not care about their relationships. They worshiped and respected Idols, and sins were clinging to them [1].

3. Who Testified to the prophethood of Muhammad (PBUH&HP) First?

Imam Ali (AS) sometimes accompanied Prophet Muhammad (PBUH&HP) when he went to Hira cave. And, the day that the Archangel Gabriel appeared before the Prophet (PBUH&HP), Imam Ali (AS) was there, too. Prophet Muhammad (PBUH&HP) said to Imam Ali (AS) that: "O Ali, you see all that I see and you hear all that I hear, except that you are not a Prophet, but you are a vicegerent and you are surely on (the path of) virtue." [3].

Afterward, being perplexed by this happening, Prophet Muhammad (PBUH&HP) went home to describe what has happened to his wife, Khadija (AS). She (AS) was the first woman who testified to the prophethood of Muhammad (PBUH&HP). And according to the authentic resources, the first man was Ali (AS) [2]. Imam Ali (AS) has described the situation like this: "In those days Islam did not exist in any house except that of the Prophet of Allah (PBUH&HP) and Khadijah (AS), while I was the third after these two." [3].

4. How Did people react to Prophet Muhammad (PBUH&HP) Claim about His Prophethood?

In the beginning and according to divine guidelines, Prophet Muhammad (PBUH&HP) did not reveal his revelations publicly. Still, it was confined to a small circle of his family, close friends, and whoever he thought was eligible. In this period, the aim was to find real loyal fellows, although few. Of course, polytheists found about it, but they did not take it seriously [4].  

Three years later, Prophet Muhammad (PBUH&HP) began to preach to his clan members by receiving the command to "Warn the nearest of your kinsfolk" (26:214). But he mostly received ridicule and mockery. Allah Almighty ordered him not to give up and make his mission publicly known: "So proclaim what you have been commanded, and turn away from the polytheists" (15:94).

The rich people of Mecca saw their power and wealth in danger with the ideas that Muhammad's (PBUH&HP) new religion proposed like social equality, sharing the wealth with needy people, and rejecting idols. On the contrary, people of the lower classes, slaves, and women were those who embraced Islam very soon [4]. 

According to the details above, Prophet Muhammad (PBUH&HP) was chosen by Allah almighty at the time when humanity was at its dawn, and morality was long disappeared among humankind. He was the one who once more reminded human beings of the concept of humanity and the reason for creation.

Notes:

[i] In the "Age of Ignorance" (before the advent of Prophet Muhammad (PBUH&HP)), people did not trust each other much and did not care about the safekeeping of others' affairs. But, everyone in Mecca trusted Prophet Muhammad (PBUH&HP), and when they went to business travels, they entrusted their valuable goods to him. So, he was given the nickname "Al-Amin." And, this title continued to be used for the Prophet (PBUH&HP) after the emergence of Islam, too, although some people had become against him since he fought idolatry. 

References:

1. "Nahjul Balaqah", Sermon 26.
2.  Allamah Amini, “Al-Ghadir”, vol. 3, p. 236.
3. "Nahjul Balaqah", Sermon 192.
4.  Jafar Morteza Amoli, “Al-Sahih Min Sirat Al-Nabi Al-Azam”