Sahih Bukhari, Vol 1, Hadith no. 15

Narrated by Anas radiyAllahuanhu: The Prophet sallaAllahu alayhi wassallam said -

"Whoever possesses the following 3 (qualities) will have the sweetness (delight) of faith:

1. The one whom Allah 'Azza wa jal and His Messenger (Muhammad sallaAllahu alayhi wassallam) become dearer than anything else.
2. Who loves a person and he loves him only for Allah's sake.
3. Who hates to revert to kufr (disbelief) as he hates to be thrown in the fire."