From Sahih Bukhari (Hadith 4154):
Narrated Jabir bin `Abdullah:On the day of Al-Hudaibiya, Allah's Messenger (ﷺ) said to us' "You are the best people on the earth!" We were 1400 then. If I could see now, I would have shown you the place of the Tree (beneath which we gave the Pledge of Allegiance)." Salim said, "Our number was
Reference: Bukhari 4154