Hadith 3846

حَدَّثَنِي عُبَيْدُ بْنُ إِسْمَاعِيلَ ، حَدَّثَنَا أَبُو أُسَامَةَ ، عَنْ هِشَامٍ ، عَنْ أَبِيهِ ، عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا ، قَالَتْ : " كَانَ يَوْمُ بُعَاثٍ يَوْمًا قَدَّمَهُ اللَّهُ لِرَسُولِهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ , فَقَدِمَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَقَدِ افْتَرَقَ مَلَؤُهُمْ وَقُتِّلَتْ سَرَوَاتُهُمْ وَجُرِّحُوا , قَدَّمَهُ اللَّهُ لِرَسُولِهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي دُخُولِهِمْ فِي الْإِسْلَامِ " .
Narrated 'Aisha: Allah caused the day of Buath to take place before Allah's Apostle was sent (as an Apostle) so that when Allah's Apostle reached Medina, those people had already divided (in different groups) and their chiefs had been killed or wounded. So Allah made that day precede Allah's Apostle so that they (i.e. the Ansar) might embrace Islam.
Hadith Reference صحيح البخاري / كتاب مناقب الأنصار / 3846
Hadith Grading محدثین: أحاديث صحيح البخاريّ كلّها صحيحة
Explanation & Benefits
Shaykh Abdul Sattar al-Hammad
Hadith Commentary:

It was possible that if the chiefs of the Ansar had been alive, they would have created obstacles for the Ansar in accepting faith or would not have allowed the Messenger of Allah (sallallahu alayhi wa sallam) to come to Madinah Tayyibah. Therefore, Allah, the Exalted, eliminated them beforehand.
Among the chiefs was Abdullah bin Ubayy, who donned the cloak of hypocrisy and continued plotting against the Muslims.
In the end, he was humiliated and disgraced at the hands of his own son.

Imam Bukhari (rahimahullah) has established from this that although the Battle of Bu'ath was fought in the era of ignorance (Jahiliyyah), it proved to be a mercy for the people of Islam.
And Allah knows best.
Source: Hidayat al-Qari: Commentary on Sahih Bukhari, Urdu, Page: 3846