Sahih Muslim Book 1, Hadith Number 73.

Chapter : Concerning the fact that it is one of the characteristics of Iman that one should like the same thing for one’s brother-in-Islam as one likes for one’s self.

It is narrated on the authority of Anas that the Prophet (may peace blessings be upon him) observed: By Him in whose Hand is my life, no, bondsman (truly) believes till he likes for his neighbour, or he (the Holy Prophet) said: for his brother, whatever he likes for himself.