From Muhammad bin Abdul Hameed from Muhammad bin Fudhail that he asked Abil Hasan ar-Reza (as) regarding reapperance and he said:

“Allah, the Might and Sublime says: Wait then, I too with you wil be of those who wait.” (Surah Yunus, 102) Then he told the following verse: “And watch, surely I too am watching with you.” (Surah Hud, 93)

(Kamal al-Din, Chapter 55, Hadith 4 and 5)

They asked Imam Riza and he in return asked to Hazrat Ali (as).

They asked Hazrat Ali (as) when would be the victorious appearance of Hazrat Ali.

Hazrat Ali said, I seek refuge in God from the accursed satan: Wait then, I too with you wil be of those who wait.” (Surah Yunus, 102) Then he told the following verse: “And watch, surely I too am watching with you.” (Surah Hud, 93)

Notice that Mahdi was awaited 1400 years ago. Hazrat Ali awaited him. Think of it, after the demise of our Prophet (saas). 

http://en.a9.com.tr/watch/208001/Adnan-Oktarin-Sohbet