Narrated 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 Messenger so that when Allah’s Messenger came to Medina, they (the tribes) had divided (into hostile groups) and their nobles had been killed; and all of that facilitated their conversion to Islam.

Bukhari, Volume 005, Book 058, Hadith Number 267