Merits of the Helpers in Madinah (Ansaar)
Bukhari :: Book 5 :: Volume 58 :: Hadith 131
Narrated Zaid bin Al-Arqam:
The Annwar said, "O Allah's Apostle! Every prophet has his own followers and we have followed you. So will you invoke Allah to let our followers be considered from us (as Ansar too)?" So he invoked Allah accordingly.