Imam Al-Hadi (a.s.) lived a short life. He died in Samarra when he was forty-one years old. He was born in the mid of Zul Hijja 212 H at "Surba", a village founded by Imam Al-Kazim (a.s.) that is three miles far from Median. Al-Hadi (a.s.) was quite knowledgeable and a scholar in various fields, which made him enrich the Islamic culture. He used to teach people, even scholars, to the extent that his narrators had reached one hundred and eighty five narrators, knowing that during that age, the narrator used to represent an advanced scholar position. Historians stated that his reliable narrators included: "Ahmad bin Hamza bin Al-Yasaa, Saleh bin Muhammad bin Al-Hamadani, Muhamad bin Gizal Al-Jammal, Yaacoub bin Yazid Al-Katib, Abu Al-Hassan bin Hilal, Ibrahim bin Ishaaq, Khairan Al-Khadim, An-Nadir bin Muhammad Al-Hamadani. Ja'far bin Sahil As-Saqil was one of his representatives, while his companions included: Dawood bin Yazid, Abu Suleiman Zankan, Al-Hussein bin Muhammad Al-Madai'ni, Ahmad Ismael bin Yakten, Bachir bin Bachar An-Naichabori Ash-Shazani, Saleem bin Jaa'far Al-Marozi, Al-Fatih bin Yazid Al-Jarjani, Muhammad bin Saeid bin Kalthoom, Mouawiya bin Hakim al-Koufi, Ali bin Ma'ad bin Al-Baghdadi and Abu Al-Hassan Ibn Raja Al-Abirtaii."
Imam Al-Hadi (a.s.) used to confront all kinds of deviation in the Islamic reality. That is because the responsibility of the prophets, Imams and the religious scholars is to study the lines that move in the Islamic culture or in the Islamic reality, in order to correct what is wrong and face the deviation by the ways that Allah, the Most Exalted, has ordered in His Book; that is by wisdom and goodly exhortation, and by arguing in the better way.
The Imam (a.s.) has faced many intellectual problems that used to impose themselves in the Islamic mentality to make Muslims deviate from the right path. Hence, during the Imam's age, there were those who adopted the concept of "compulsion" and claimed that Allah obliges people to commit sins and disobedience and then He punishes them for that.
Another group of people adopted the concept of "free will". It is the concept of saying that Allah has authorized His creations to choose their actions without any interference except by the Prophets who guide the people to the right path.
It seems that the proponents of these two concepts were outside the Medina and Imam Al-Hadi sent them a letter explaining what is right, and proved with irrefutable, scientific proofs the falsity of the two concepts "compulsion" and "free will". He called upon them to follow the right path, which is the path of Allah, the Most Exalted. The Imam (a.s.) also faced the exaggerators who tried to make people believe their myths, especially that most mentalities in the society are simple-minded that believe anything said to them, and this might happen everywhere and place. He (a.s.) says in this letter:
"From Ali bin Muhammad, peace, mercy, and blessings of Allah be upon you and upon whoever follows the guidance. Your book came to me and I understood what you mentioned of your disagreement in your religion, your plunging in the matter of “fate”, the belief of some of you in “compulsion”, and others in “free will”, and the disagreement, separation, and enmity among you because of that. Then you asked me about that and to explain it you. I understood all that…As for “compulsion”, it is the belief of those who claim that Allah forces people to commit sins and disobediences and then He punishes them for that. Whoever believes in this concept wrongs Allah, falsifies Him and denies His saying, (and your Lord does not deal unjustly with anyone) and, (This is due to what your two hands have sent before, and Allah is not in the least unjust to the servants) and, (Surely Allah does not do any injustice to men, but men are unjust to themselves) besides many other verses in this concern. He, who claims he is forced into disobedience, ascribes his sins to Allah and considers Allah as unjust in punishing him. Whoever considers Allah as unjust denies His Book, and whoever denies His Book must be unbeliever due to the consensus of the nation…. As for the concept of “free will”, which Imam as-Sadiq (a.s.) refuted, it is the concept of saying that Allah the Almighty has authorized His people to choose His enjoinments and prohibitions and He neglected them. The infallible imams of the Prophet’s progeny say that if Allah has authorized people and neglected them, then he must be pleased with what they choose and they deserve reward for that and should not be punished for sins they commit if indeed there is negligence… He, who claims that Allah has entrusted His orders and prohibitions to His people, describes Allah as unable and consequently He must accept all that which His people do whether good or bad. This one also denies the orders, prohibitions, warnings and threatening of Allah. When one claims that Allah has entrusted all that to man, it means that man is free to believe or disbelieve and he shall not be blamed for that. He, who believes in “free will” in this meaning, denies the orders, prohibitions, warning, and threatening of Allah and he is one of those who are included in this verse, (Do you then believe in a part of the Book and disbelieve in the other? What then is the re ward of such among you as do this but disgrace in the life of this world, and on the day of resurrection they shall be sent back to the most grievous chastisement, and Allah is not at all heedless of what you do). Allah is too far above that which the people of “free will” believe in…".
‘But we say: Allah the Almighty created people by His power and gave them the ability of obeying Him. He ordered them to do what He wanted and forbade them from what He wanted. He accepted from them their obedience to His orders and He pleased it, and He prohibited them from disobeying Him, dispraised the disobeyers, and punished them for that. Allah has the choice of enjoining His people on doing some things that He pleased and forbidding them from other things that He hated. He punishes for disobediences due to the ability he has given to His people by which they can obey Him and avoid His prohibitions because He is just, fair, wise, and has clear excuses. He chooses from among His people as He wills to inform of His mission and authority over people. He chose Muhammad (a.s.) and sent him with His mission to His creation…"
In the Imam's age, a group of people claimed that the Imam is god and the prophet and that the prayers that forbid evil and wrongdoing are performed through knowing the Imam. Those who adopted this concept exploited people's love to Ahl-el-Beit (a.s.) to spread these concepts. Hence, a follower of Imam Al-Hadi (a.s.) sent him (a.s.) a letter in which he said: "May my soul be sacrificed for you my master. Ali Bin Hasaka, an exaggerator, claims that he is one of your followers and that you are the First and the Infinitely Preexistent and that he is your prophet. He said that you have ordered him to call for that and claimed that the prayer, zakat, hajj, and fasting is knowing you and knowing those who were like Ibn Hasaka who claim to be prophets and that the one who knows them will be a perfect pious person and will be also exempted from praying, fasting and performing hajj – meaning he will no more be obliged to perform hajj, praying and fasting. So, would you give your followers (Shiites) an answer for that in order to save them from being perished."
The Imam (a.s.) wrote to him saying: Ibn Haska has lied. I do not know him and he is not among my followers. What does he want? I swear by God that God has neither sent Mohammad nor the Prophets before him except for the unification of Allah, prayer, Zakat, hajj, fasting, and for wilayah. Muhammad (p.) has called for worshipping Allah only, the One. We are the Awsiyaa among his (p.) progeny, the servants of Allah. We do not take anything as partner to Him. If we obey him, he will have mercy upon us and if we disobey him he will torture us. We have no plea against Allah, but He has plea against all His creatures. I am innocent of those who say such claims…
This letter emphasizes that Ahl el-Beit denied exaggeration that raises the Imams to the level of Divinity in a direct manner through saying that Allah is embodied in them and through other ways, or in an indirect manner through claiming that they enjoy Allah's characteristics, and therefore we have to worship them. They also claimed that the subsistence is form them and that they cause life and death …
The Imam quietly rejected these concepts through emphasizing their slavery to Allah and that they are commanded to obey His orders. If they disobey Him, they will be punished. Hence Allah has a plea against them as well as against all His creatures, while they do not have a plea against Him, for they are His servants. Besides, the Imam announced that he is innocent from those people through clearing himself from this deviated thought and calling upon his followers to confront them… Therefore, we have to open on the Imam's thought and refuse all kinds of deviation that call for exaggeration or claiming that the Imams possess divine positions as if they were playing Allah's role in creating, blessing, giving life, causing death…etc.