Hazrat Ali, Amir al-Muminun narrated from our Prophet (saas) as follows : “The most superior of the acts of worship is to await the appearance of Hazrat Mahdi.” Our Prophet (saas) mentions the Unity of Islam, the Unity of Islam and the need for a leader.
Imam Sadiq said :
“Whoever dies in awaiting Ahl Bayt, he becomes like one in the army of the Qaim, the Hazrat Mahdi (as). " This means that if a person dies with the intention of being a follower of Hazrat Mahdi, he earns equal merit with a person who is from Hazrat Mahdi’s army. It is very important to have intentions. Seeking Hazrat Mahdi (as), loving Hazrat Mahdi (as), if one is sure that he is alive, experiencing in his soul his submission and deep love for him. If this becomes the case, our Prophet (saas) says that that person earns merit as if he had struggled in the army of Hazrat Mahdi (as) all through his life.
Our Prophet (saas), “ Before his advent, in the period of Ghaybah’, We can say during the period he was not seen, imprisoned or he was hiding. ‘They ask our Prophet (saas), What will be the benefit of the existence of Hazrat Mahdi (as) ?’ That is to say, it is hidden, you can not see him, so what is the benefit of his existence ? And our Prophet (saas) answers:
“I swear on Allah Who sent me as a prophet that during the time people cannot see Hazrat Mahdi (as), people benefit from Hazrat Mahdi (as) as if they benefit from the Sun remaining behind the clouds.” That is to say, the Sun exists, it is light but they can't see it, it is behind the clouds but it is still day. The reason for that light is Hazrat Mahdi (as). In other words, even if you don’t see him, you benefit from him. But when he appears, you see him under all circumstances. That is what our Prophet says (saas).
Imam Sadiq (as) narrated from Imam Zayn al –Abidin : “If Hazrat Mahdi (as) did not exist, nobody would duly worship Allah.” That is said for the End Times. In other words, the dajjal would be all over the world so the Mahdi will be instrumental in people’s duly worshiping Allah.