From Sahih Bukhari (Hadith 3844):
Narrated Ghailan bin Jarir:We used to visit Anas bin Malik and he used to talk to us about the Ansar, and used to say to me: "Your people did so-and-so on such-and-such a day, and your people did so-and-so on such-and-such a day
Reference: Bukhari 3844