جامع الترمذي

Zaid bin Arqam wrote to Anas bin Malik, comforting him over those of his family and children of his paternal uncle who suffered on the day of Al-Harrah. So he wrote to him: "I give you glad tidings of good news from Allah. I heard the Messenger of Allah (ﷺ) say: 'O Allah forgive the Ansar and the children of the Ansar, and the children of their children."