Narrated Anas: Allah's Apostle (peace be upon him) said, "Whoever possesses the (following) three qualities will have the sweetness of faith (1): The one to whom Allah and His Apostle becomes dearer than anything else; (2) Who loves a person and he loves him only for Allah's Sake; (3) who hates to revert to atheism (disbelief) as he hates to be thrown into the Fire."

Sahih Bukhari Volume 9, Book 85, Number 74