Imam Jafar-e-Sadiq A.S has said : "From among us there will be an Imam who will live in occultation whose period will be very long." He was asked why it would be so and the holy Imam answered:" It is the will of Allah that the ghaybat which is one of the characteristics of the Prophets will continue through the Imam-e-Qayam A.S. Therefore the period and the time of length of the concealment of the 12th Imam A.S will be a total of the length of ghaybat of all particular Prophets.
Imam Zain-ul-Abedeen A.S has said that:" The one among us who will be the Qayam will inherit the signs of many prophets. One sign of Hazrat Adam A.S , one of Hazrat Nooh A.S , one of Hazrat Ibraheem A.S , a sign of Hazrat Musa A.S , a sign of Hazrat Eesa A.S , one of Hazrat Ayyoub A.S , and also a sign of Hazrat Muhammad Mustafa S.A.W. The indication connected to Hazrat Adam A.S and Hazrat Nooh A.S will be His long life , next His concealed birth and being beyond the reach of anyone will resemble the life of Hazrat Ibraheem A.S. The sign connected to Hazrat Musa A.S will be the part of ghaybat and the fear of being discovered and martyred. The perplexity about the fact of that He is alive or dead will resemble the doubts of Hazrat Eesa A.S , the sign of Hazrat Ayyoub A.S will be the appearance after trials of the faithfuls and last the sign of the Last Prophet S.A.W will be when Imam Mehdi A.S will reappear with a sword in His hand!
The invisibility of the 12th Imam A.S is not the fault of the Shias or a punishment for their sins. To keep the last Imam hidden is the will of Allah Almighty . Allah has the power of all , if He wish He can turn the face black whenever someone commits a sin but He does not do so and that is because it is against His will. It is the same of His plan and wish of the proper time of the reappearance of Imam Mehdi A.S. If our Lord desire , the advent of Imam-e-Asr A.S can be witnessed today but still this has not happened yet which is a sign of that Allah the Almighty has not given the signal.
It is a clear fact that the opponents and enemies of Islam are continuing to commit sins and vices and there are some among the category of people who have faith in the Imamat of the 12th Imam A.S who are also guilty of many sins. The sad part is that the innocent true faithful momeneen and momenaat are without the directly guidance of Imam-e-Hujjat A.S. But eventhough the holy Imam of the Age is hidden to these people it doesn't jeopardize their trust and faith in His existens. Allah Almighty extends the reward of their waiting and we all should know that our holy Imam A.S will not only guide His followers after His reappearance but they will benefit from Imam Mehdi A.S even during ghaybat as people benefit from the rays of the sun although obscured by clouds.