Musnad Ahmad 580:1

Yazid ibn Harun narrated to us, Muhammad ibn Amr informed us, from Sa’d ibn al-Mundhir ibn Abi Humayd al-Sa’idi, from Hamzah ibn Abi Usayd, who said: I heard al-Harith ibn Ziyad, a companion of the Messenger of Allah, peace and blessings of Allah be upon him, say: The Messenger of Allah, peace and blessings of Allah be upon him, said: "Whoever loves the Ansar, Allah will love him when he meets Him, and whoever hates the Ansar, Allah will hate him when he meets Him."