Sahih Bukhari Volume 009, Book 085, Hadith Number 074.

Narrated By Anas : Allah's Apostle said, "Whoever possesses the (following) three qualities will have the sweetness of faith:

The one to whom Allah and His Apostle becomes dearer than anything else;
Who loves a person and he loves him only for Allah's Sake;Â
Who hates to revert to atheism (disbelief) as he hates to be thrown into the Fire."

Sahih Bukhari