His birth (peace be upon him):
He (peace be upon him) was born in the village of Sarba near Madinah, on Tuesday, the second of the month of Rajab in the 212 AH, which is confirmed in the famous Rajab supplication: "O Allah I ask You in the name of two grand personalities born in month of Rajab-Mohammad the son of Ali and his son Ali ibn Mohammad."
His name (peace be upon him):
Imam Ali son of Mohammad son of Ali son of Musa son of Ja'far son of Mohammad son of Ali son of al-Hussayn son of Ali ibn abi Taleb (peace be upon them).
His nickname (peace be upon him):
Abu al-Hassan, and also Abu al-Hassan the third, a distinction to him from Imam Ali ar-Reda (peace be upon him) as he is Abu al-Hassan the second.
His titles (peace be upon him):
al-Hadi, al-Mutawakkil, al-Fattah, al-Naqi, al-Murtadha, al-Najib, al-'alim, and he is most known by al-Hadi.
His mother and wife:
His mother is Lady Sumanah the Moroccan and she is a slave. His wife is Lady Sawsan and she is also a slave.
His age and Imamate:
He has 42 years old, and his Imamate was for 33 years.
The rulers of his time:
al-Mu'tassim, al-Watheq, al-Mutawakkil.
From the words of Imam al-Hadi (peace be upon him):
1- He (peace be upon him) said: "Whoever is selfish and self-satisfied, people will soon be infuriated at them."
2- He (peace be upon him): "The grievance for the person who is patient is single, but for the one who laments and wails is double."
- He (peace be upon him): "Idle talking and joking is a character of the unwise and the feature of the ignorant."
- He (peace be upon him): "Staying awake for long makes sleeping enjoyable and bearing much hunger increases the joy and delight of eating."
- He (peace be upon him): "Remember your death in front of your family, when there will be no doctor to prevent it from you and no beloved to help you."
His scientific status (peace be upon him):
Sheikh Tousi has stated in his book that there were some one hundred and eighty five students and narrators of Imam al-Hadi (peace be upon him).
His miracles (peace be upon him):
The Imam al-Hadi (peace be upon him) has many miracles, including:
"It is narrated that al-Mutawakkil one day brought three lions to his palace, he then invited Imam Hadi (peace be upon him) and entered him to the palace and closed the door behind him, leaving him with the lions, Imam Hadi (peace be upon him) was seen with lions around him while he touched them on head with his palm. Al-Mutawakkil to his surprise and fear, opened the door and let Imam Hadi go. It is also narrated that those around al-Mutawakkil asked him to do like his "cousin", he told that that they only wanted to see him dead.”