VERY FEW PEOPLE WILL BELIEVE IN HAZRAT MAHDI (AS) IN THE TIME OF HIS OCCULTATION, AND EVERYONE ELSE WILL HARBOR DEEP SUSPICIONS ABOUT HIM

... Know that the occultation of my son [Hazrat Mahdi (as)] WILL BE VERY LENGTHY. SO MUCH SO THAT APART FROM THOSE WHOSE FAITH IS PRESERVED BY ALLAH, EVERYONE WILL HARBOR SUSPICIONS ABOUT THIS MATTER.

Bihar Al-Anwar, vol.51, p.160;
Isbat al-Hudat, vol.6, p.427.