It is narrated from Nadr bin Anas that Sayyiduna Zaid bin Arqam (may Allah be pleased with him) wrote to Sayyiduna Anas bin Malik (may Allah be pleased with him) during the days of the incident of Harrah to console him over the killing of his children and members of his tribe, and said: I want to give you glad tidings from Allah Almighty. I heard the Messenger of Allah (peace and blessings be upon him) say: O Allah! Forgive the Ansar, their sons, and their grandsons. Forgive the women of the Ansar, the wives of the sons of the Ansar, and the women of the grandsons of the Ansar.
Hadith Referenceالفتح الربانی / كتاب الفضائل والمناقب / 11538