The twelfth Imam, Muhammad al-Mahdi (may Allah hasten his appearance) was born on the 15th of Sha`ban in the year 255 AH in Samarra. His imamat began at the age of five when his father died in 260 AH. His name (Muhammad) and his agnomen (Abu 'l-Qāsim) are the same as that of the Prophet of Islam.

His father was the eleventh Shi‘a Imam, Imam Hasan al-`Askari; and his mother was the great lady Nargis (may the peace of Allah be with them both).

For various reasons, the Twelfth Imam, did not appear publicly; and for about seventy years, people were in communication with him through the intermediary of his special agents, in order of succession: `Uthman bin Sa`id, Muhammad bin `Uthman, Husayn bin Ruh, and ‘Ali bin Muhammad as-Samarri. This period of seventy years is known as the minor occultation (al-ghaybatu 's-sughra) and at the end of that period began the major occultation (al-ghaybatu 'l-kubra).

During the major occultation till the time of re-appearance, no one has been appointed as his special representative. As for legal issues, the people have the duty of referring to the fuqaha and mujtahids—those excelling in knowledge of the Islamic laws.

1. Belief in Al-Mahdi & the Universal Reform

The belief in the re-appearance of the expected Mahdi, the universal reformer is not confined to the Shi‘a Muslims. Other Islamic groups and even non-Muslims like the Jews and the Christians believe in the appearance of a great spiritual reformer. In Psalm 37, we read:

“...Trust in the Lord and do good; so you will dwell in the land and enjoy security...
For the wicked shall be cut off; but those who wait for the Lord shall possess the land...
But the weak shall possess the land, and delight themselves in abundant prosperity...
The Lord knows the day of the flawless, and their heritage will abide forever...
For those blessed by the Lord shall possess the land, but those cursed by Him shall be cut off...
The righteous shall possess the land, and dwell upon it for ever...”

2. The Qur’ān & the Belief in al-Mahdi

Allāh has promised the believers and worshippers of the True God that a time will come when they will take over the power of the world, and the glorious religion of Islam will reign all over the earth.

For We have written in the Psalms, after the remembrance, `My righteous servants will inherit the earth.' (21:105)

Allah has promised those of you who believe and do righteous deeds that He will surely make you successors in the land just as He made those who were before them successors, and that He will surely establish their religion for them, and will give them in exchange, after their fear, security: `They shall serve Me, not associating with Me anything.' (24:55)

It is He who has sent His Messenger with the religion of truth, that he may lift it above every religion, though the unbelievers be averse. (61:9)

We desire to be gracious to those who were abased in the land, and to make them leaders, and to make them the inheritors. (28:5)

The above verses clearly show that in the end the world will fall into the hands of Allāh’s worthy and righteous servants and that they will become the leaders of the people of the world. Then Islam will be victorious over all religions.

3. Belief in the Mahdi & Sunni Authorities

In this subject, the scholars in the Sunni school have related many hadiths from the Prophet of Islam through trustworthy narrators. From among them are ahadith which say that the Imams are twelve persons and that they are all from the Quraysh.

Al-Mahdi, the promised one, is from the family of the Prophet and a descendent of Imam ‘Ali and Fatimah az-Zahra, and in many ahadith it is mentioned that he is from the line of Imam Husayn. The Sunnis have mentioned and recorded hundreds of ahadith about the Mahdi in more than seventy books through their own authorities of which we shall just mention a few examples:

Al-Musnad of Ahmad bin Hanbal (d. 241 AH).
Sahih of al-Bukhāri (d. 256 AH).
Sahih of al-Muslim (d. 261 AH).
Sunan of Abu Dāwud as-Sajistāni (d. 275 AH).
Sahih of at-Tirmidhi (d. 279 AH).

The authors of the above books are among the most authoritative books of the Sunnis and, more interestingly, all died either before the birth of the Twelfth Imam (255 AH) or shortly after his birth.

4. The Hidden Reformer

We have at least three hundred ahadith from the Prophet and from five Imams about Imam al-Mahdi (a.s.). From these ahadith, it is clear that the Mahdi is the ninth son of Husayn bin ‘Ali; that his father is Hasan al-‘Askari and his mother is Nargis Khatun; that his name is the same as that of the Last Prophet; that the Mahdi would be born during his father's lifetime in Samarra; that his father would die when he would be young; that he will live as long as God wished it; that he will re-appear and the world will be filled with justice and equality at a time when there will be injustice everywhere.

And when he comes —may God hasten his appearance— he will lean against the Ka‘bah and cry out and call for his followers, who will number 313 persons. Prophet ‘Isa (Jesus) will come from the heaven down to the earth, and will pray behind the Mahdi. The Twelfth Imam will enforce the commands of Islam all over the world; and the earth will be like heaven.

There are many ahadith related by the Shi‘a and Sunni scholars on many aspects connected with this great Imam, and these are mentioned in books like Bihāru ’l-Anwār of ‘Allāmah Majlisi (d. 1010 AH) and Muntakhabu ’l-Athar of Shaykh Lutfullah as-Safi.

When we look at the ahadith on this subject, we come to realize the ahadith mentioning al-Mahdi (a.s.) have been narrated most frequently, and that there are few subjects in Islam which have been mentioned in hadith so often. Thus, in this light, anyone who believes in Islam and its Prophet must necessarily declare his belief in the existence of the promised Mahdi who is now in occultation.

Now we shall relate two ahadith on this issue from the famous Sunni book, Yanābi‘u 'l-Muwaddah:

1. The Prophet said, “Al-Mahdi is a descendent of mine. He will be in concealment, and when he manifests himself, the earth will become filled with justice just as it was previously filled with injustice.”

2. Salman al-Farsi says that he went to the Prophet when Husayn bin ‘Ali was sitting in his lap and the Prophet was kissing his eyes and mouth, and then the Prophet said to Husayn, “You are a chief, son of a chief, and the brother of a chief; you are an Imam, son of an Imam, and the brother of an Imam. You are the Proof (hujjah), son of a proof and the brother of a proof; you will be the father of nine proofs of whom the ninth will be the qā'im (one who will establish the divine rule on this earth).”

5. The Length of al-Mahdi’s Life

We believe that the lengthening of a man's life is not an impossibility, because it is explicitly stated in the Qur'ān that, “We sent Nuh to his people and so he lived among them a thousand years, all but fifty.” (29:14) Even modern science does not deny the possibility of lengthening the human lifespan.

If a greatly extended life is not an impossible event, there is nothing to prevent God from keeping a man alive for thousands of years because the regulations of a man's life is in the hands of God. He can bring a new order into existence which has precedence over the usual order of things, just as He did in the case of all the miracles. The miracles of the prophets: the cooling of the fire for Ibrahim, the turning of Musa’s staff into a serpent; bringing the dead to life through `Isa, and so forth, are all against the usual flow of things but God brought another order into existence by His own power and a miracle occurred. All the Muslims, the Jews and the Christians believe in these miracles.

Similarly, for the length of the life of Imam Mahdi, there remains no place for any kind of objection, because if someone says that such a length of life is impossible, then his claim cannot be at all accepted after the stipulation of the Qur'ān concerning the length of Prophet Nuh's life. If someone says that a prolonged life is possible but against the normal natural order of things, then it can be retorted that the length of life of Imam Mahdi is against the natural order just as the miracles of the prophets are against the natural order but within the power of God.

Someone who believes in the power of God and in the miracles of the prophets cannot have the slightest objection to the length of Imam Mahdi’s life.