Sahih Muslim Book 1, Hadith Number 68.

Chapter : Concerning the attributes by which one gets the relish of Iman.

It is reported on the authority of Anas that the Messenger of Allah (may peace be upon him) said: There are three qualities for which any one who is characterised by them will relish the savour of faith: that he loves man and he does not love him but for Allah’s sake alone; he is to whom Allah and His Messenger are dearer than all else; he who prefers to be thrown into fire than to return to unbelief after Allah has rescued him out of it.