Moment by moment expectation due to the unpredictability of the time of rising

The Shea authorities narrated:

Imam al-Sadiq (AS) said to his companions, "Be more hopeful on the things that you consider far-fetched than that which you presume very likely. Verily, Musa Ibn Imran (AS) went to bring fire (to provide heat and light) for his family and he came back to them while he was an Apostle, and this way, Allah rectified the matter of His servant and His Prophet, Musa (AS), within a night. In the same way Allah shall treat al-Qa'im, the twelfth of the Imams (AS). He shall rectify his matter in one night and shall take him from discomfort and concealment into the light of relief and reappearance."

There are many other Shea transmitted traditions, which convey the similarity of the sudden advents for some ancient Prophets (AS) with that of Imam Mahdi (AS).

The following tradition also shows that we should expect the rising of al-Qa'im at every moment and make ourselves ready for his arrival because his coming is very unpredictable. It is narrated:

The notion of continual awaiting/expecting and hoping to see the golden day of the earth at any moment has many positive benefits in our lives. It constantly reminds us the absolute power of Allah. A faithful servant who believes Allah has power to do all things, does not consider anything far-fetched for Him. Moreover, so long as we expect the Imam (AS), we are hopeful for a better future and will not be disappointed by the difficulties and the problems of our present life no matter how severe they are. In addition, when we realize that Allah may advance the advent of al-Qa'im (AS) to a very near future, we do our best to prepare our spiritual state to receive him. In the last part of this work, we will discuss our duties as the expectant of al-Qa’im (AS), which would lead to Allah's satisfaction so that Allah might decide to waive the remaining time of occultation.

As we have seen, the existence of al-Badaa plays a central role in our way of expecting al-Qa'im (AS). Due to the possibility of Badaa, the fore-told signs are subject to change. If the signs were unchangeable there would be no point to wait all the time and in every moment. Having faith in change and alteration by Allah, everyone would keep himself ready every morning, every evening and all the time in between to receive the Imam (AS). According to the traditions, waiting for the Imam (AS) at any moment is the best deed and the most significant act. Such action is meaningful only when the changes in the aforementioned signs are possible. A person who has no faith in alteration of signs and thinks of the reappearance of Imam (AS) after sighting of the signs is actually waiting primarily for the sighting of signs and then for the Imam (AS). Such an individual may deny Imam al-Mahdi (AS) if he reappears without the signs being fulfilled. To the contrary, the traditions give prime importance to the promise of the reappearance of the Imam (AS) and consider the appearance of the signs as an inferior issue. Abu Ubaida al-Hadhaa narrated:

It is now clear that we should wait for the reappearance of Imam (AS) and not for the sign, and should not consider reappearance before witnessing the foretold signs impossible. It is only in this situation that imploring Allah to hasten the reappearance of Imam (AS) is meaningful. Allah is free to shower His blessings any time He wants. He has created a leader for this task so long ago and has kept him on call in concealment. He can order the reappearance of the Imam (AS) even before the sighting of signs or can change the signs for his early rise. Much more than any of His followers, our Imam (AS) is eagerly waiting for receiving Allah's permission at any moment.

Source: alhassanain.com

Other links:

The signs before reappearance of al-Mahdi (A.S)

The possibility of canceling the signs of the reappearance of Imam Mahdi (A.S)

The Doctrine of Mahdiism and its Impact

Terminology of the Mahdiism Doctrine