Musnad Ahmad 28:464

Yazid narrated to us, Hajjaj ibn Artah informed us, from Amr ibn Shu'ayb, from his father, from his grandfather, who said: A man came to the Messenger of Allah, peace and blessings of Allah be upon him, and said: "O Messenger of Allah, I have relatives; I maintain ties with them while they sever them, I pardon them while they wrong me, and I treat them well while they treat me badly. Should I retaliate against them?" He said: "No, for then you would all be abandoned. Rather, take the path of virtue and maintain ties with them, for there will continue to be a supporter for you from Allah as long as you are upon that."