Mukhtasar Bukhari

Umm al-Mu'mineen Aisha Siddiqa (may Allah be pleased with her) says: The Day of Bu'ath was a day which Allah brought before His Prophet (peace be upon him) (there was great wisdom in it). When the Prophet (peace be upon him) arrived in Madinah, the condition of the Ansar was such that division had spread among them, some of their leaders had been killed and some wounded. Allah brought that day forward for His Prophet (peace be upon him) so that when he arrived, they would accept Islam.