[Machine] When the Messenger of Allah ﷺ left Makkah, Abu Bakr said, "Indeed, to Allah we belong and to Him we shall return." [Quran 2:156] The Messenger of Allah ﷺ was expelled to be destroyed, so this verse was revealed, "Permission [to fight] has been granted to those who are being fought, because they were wronged. And indeed, Allah is competent to give them victory. Those who have been expelled from their homes unjustly" [Quran 22:39-40]. Abu Bakr realized that there would be a battle.
لَمَّا خَرَجَ رَسُولُ اللَّهِ ﷺ مِنْ مَكَّةَ قَالَ أَبُو بَكْرٍ {إِنَّا لِلَّهِ وَإِنَّا إِلَيْهِ رَاجِعُونَ} [البقرة 156] أُخْرِجَ رَسُولُ اللَّهِ ﷺ لَيَهْلِكَنَّ قَالَ فَنَزَلَتْ هَذِهِ الْآيَةُ {أُذِنَ لِلَّذِينَ يُقَاتَلُونَ بِأَنَّهُمْ ظُلِمُوا وَإِنَّ اللَّهَ عَلَى نَصْرِهِمْ لَقَدِيرٌ الَّذِينَ أُخْرِجُوا مِنْ دِيَارِهِمْ بِغَيْرِ حَقٍّ} [الحج 40] عَرَفَ أَبُو بَكْرٍ أَنَّهُ سَيَكُونُ قِتَالٌ