The Day of Buath was a day Allah prepared in advance for His Messenger ﷺ. By the time the Messenger of Allah ﷺ arrived, their assembly had been split apart, their nobles slain, and many wounded. So Allah set this day before His Messenger ﷺ as a means for their entry into Islam.
كان يوم بعاث يوما قدمه الله لرسوله ﷺ. فقدم رسول الله ﷺ وقد افترق ملؤهم، وقتلت سرواتهم، وجرحوا. فقدمه الله لرسوله ﷺ في دخولهم في الإسلام.
Bukhari narrated it in the Merits of the Ansar (3777), from Ubayd bin Ismail, who said, Abu Usama narrated to us, from Hisham, from his father, from Ayesha, and she related it.Buath is the place where the war took place between Aws and Khazraj. The leader of Aws, Hudayr, the father of Usayd bin Hudayr, was there, and the leader of Khazraj, Amr bin Numan Bayadi, was also killed there. Victory went first to Khazraj, then to Aws. This happened five years before the arrival of the Prophet ﷺ.Her saying "sarawat" is the plural of "sarah," which means a person of noble rank.