Musannaf Ibn Abi Shayba 27:718

Yazid ibn Harun narrated to us, he said: Yahya ibn Sa'id informed us that Sa'd ibn Ibrahim informed him, from al-Hakam ibn Mina, from Yazid ibn Jariya, that he was sitting among a group of the Ansar. Mu'awiya passed by them and asked them about their conversation. They said: "We were in a conversation regarding the affairs of the Ansar." Mu'awiya said: "Shall I not add to you a hadith I heard from the Messenger of Allah, may Allah bless him and grant him peace?" They said: "Yes, O Commander of the Faithful." He said: "I heard the Messenger of Allah, may Allah bless him and grant him peace, say: 'Whoever loves the Ansar, Allah loves him, and whoever hates the Ansar, Allah hates him.'"