Ikmaaluddin: Shaykh Saduq (r.a.) has narrated from his father from Ali from his father Muhammad bin Fadhl from his father from Mansur bin Saiqal that Imam Ja’far Sadiq (a.s.) said:
“That time [of appearance of Mahdi] shall not come to pass but after you have become despondent and hopeless. No, I swear by Allah, till you are separated from each other. No I swear by Allah, till you are severely tested. No I swear by Allah, till the time that the unfortunate ones become unfortunate, while the fortunate ones become fortunate.”
[The Promised Mahdi, Allamah Muhammad Baqir al-Majlisi, Biharul Anwar, Volume 13 (Old Edition)/Volumes 51-52-53 (New Edition)]