Sahih Bukhari Volume 005, Book 058, Hadith Number 267.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 58. Merits of the Helpers in Madina (Ansaar)
Narated By 'Aisha : The day of Bu'ath was a day (i.e. battle) which Allah caused to take place just before the mission of His Apostle so that when Allah's Apostle came to Medina, they (the tribes) had divided (into hostile groups) and their nobles had been killed; and all that facilitated their conversion to Islam.