Necessity Of Recognising the Imam Of The Time

Usman Al Amri says:
"I asked Abu Mohammed Al Hasan bin Ali (A.S.) when I was in his presence, regarding the saying of his forefathers (A.S.) that, 'The earth shall never be devoid of Allah's proof upon His creatures till the day of quiyamat. And certainly one who dies without recognising the Imam of his time, dies the death of Ignorance".

He (A.S.) said, "This is as true as the bright morning".

It was asked to him (A.S.),
"O son of the Prophet (S.A), then who is the Hujjat and the Imam after you?".

He (A.S.) said,
"My son, Muhammed. He is the Imam and the Hujjat after me. One who dies without recognising him, dies the death of Ignorance".
(Kamaaluddin Vol.2 Pg.409, Kifayatul Asar Pg.292)
According to Imam Jafar as Sadiq (A.S.)the death of ignorance is the death in a deviated and astrayed condition.
(Al Kafi Vol.1 Pg.376)
The importance of recognising the Imam of the time is also clear from the following tradition. When Zurarah asked Imam Jafar as Sadiq (A.S.), "What should I do if I reach the time of his ghaibat ?".
Imam (A.S.) replied, "Recite this Dua;
'O Allah, make me recognise Your Self. 
Certainly if You do not make me recognise Your Self, I will not recognise Your Messenger. 
O Allah make me recognise Your Prophet. 
Certainly if you do not make me recognise Your Prophet, I will not recognise Your Hujjat. 
O Allah ! make me recognise Your Hujjat. 
Certainly if You do not make me recognise Your Hujjat I mil go astray in my religion."

(Kamaaluddin Vol.2 Pg.342.343; Ghaibate Nomani Pg.166:Al Kafi VoU PgJ37)