Sahih Muslim Book 1, Hadith Number 138.

Chapter : The love of Ansar (helpers) and ‘All (may Allah be pleased with all of them) is (an Ingredient) of Iman and (one of) its signs, and hatred against them is a sign of dissemblance.

Al-Bara reported it from the Apostle(may peace and blessing be upon him) that he observed with regard to the Ansar, None but the believer loves them, none but the hypocrite hates them. He who loved them loved Allah and he who hated them hated Allah. I (the narrator) said: Did you hear this hadith from al-Bara’? He said: To me, he narrated it.