One of the major responsibilities of Imam Hassan al-Askari (A.S), for which he endeavored earnestly, was to introduce the Imam after him to the Shiites and to inform them of the next Imam's occultation. At the time, the Abbasid dynasty, having had heard the words of the previous Imams (A.S) and those of Prophets' (A.S. about the savior that would be born to Imam Hassan al-Askari (A.S), were in close watch of Imam Hassan's (A.S) residency to make sure he would not have a son. Thereupon, Imam Hassan al-Askari (A.S) had to hide his son from the guards sent by the government and in that manner save his son's life. After the martyrdom of Imam Hassan al-Askari (A.S), Imam Mahdi (A.S) went into the periods of his short and long occultation, whereupon most Shiites were deprived from seeing their Imam. Upon this matter, at the time of Imam al-Askari (A.S) it was necessary to introduce Imam Mahdi (A.S) to certain Shiites, and clarify his processes of occultation. Many narrations have been recorded on this matter, but in this excerpt we will refer to only one.
Ahmad ibn Is'haq, one of the reliable companions of Imam Hassan al-Askari (A.S), has narrated: "In one of my visits to the Imam, I had intended to ask about his successor. Yet before I had spoken, the Imam (A.S) said: 'O Ahmad ibn Is'haq! From the creation of Adam, Allah (SWT) has never left the earth without His successor on people, and will never do so until the Day of Judgment…'
I asked: 'O son of the messenger of Allah! So who is the successor and Imam after you?'
Imam Askari (A.S) stood up immediately, and entered the house. He then returned carrying a three year old boy, whose face was filled with a halo of light. He said:
'O Ahmad! If it were not for your eminence in the eyes of Almighty Allah and His chosen people, I would not have shown you my child. His name and nickname are the same as that of Prophet Muhammad's (PBUH); and it is he who will fill the earth with justice after it has been corrupted with oppression…
By Allah (SWT)! He will live through a long occultation from which people will not survive perdition and deviation, except for those who stand firm on believing in his Imamate, and those who are honored with the opportunity to pray for haste in his reappearance."
Ahmad ibn Ishaq narrates: "the minute I asked Imam Askari (A.S): 'Will any sign or miracle appear to make me confident?' the child began speaking:
'I am the remainder of Allah (Baqiatullah) on earth; the one who will take revenge on the enemies of Allah; and after seeing me, do not search for any other signs!"…
(Selection taken from," An Analysis of the Life of Imam Hassan Askari (A.S)", by Muhammad Baqir Qurashi)