Narrated by Ali ibn Abu Talib (may Allah be pleased with him)
Allah's Messenger (peace & blessings of Allah be upon him) said:
No servant will be a believer
(in the true sense of the term)
till he affirms his faith in four things:
He bears witness to the fact that
there is no god but Allah..
I am His Messenger
whom He has sent with Truth.
He affirms his faith in death
and in the life after death.
He affirms his faith
in the Divine Decree.
Transmitted by Tirmidhi and Ibn Maja