Kathir bin 'Abdullah bin 'Amr bin 'Awf narrated from his father:
That his grandfather said: "The Messenger of Allah said: 'May Allah have mercy on the Ansar, and the children of the Ansar, and the grandchildren of the Ansar.'" (RU)
English reference (RU): Vol. 1, Book 1, Hadith 165 (RU)
Arabic reference (RU): Book 1, Hadith 170 (RU)