Awf bin Salamah bin Awf (may Allah have mercy on him) narrates from his father, from his grandfather (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: "O Allah, forgive the Ansar, the sons of the Ansar, the sons of the sons of the Ansar, and the freed slaves of the Ansar."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15243