Narrated It was narrated that Ibn Abbas said:

“When the Prophet (ﷺ) was expelled from Makkah, Abu Bakr said to him: ‘They have driven out their Prophet, verily to Allah we belong and to Him we return. They are surely doomed.’ Then it was revealed: ‘Permission to fight (against disbelievers) is given to those (believers) who are fought against, because they have been wronged; and surely, Allah is able to give them (believers) victory.’ Then I knew that there would be fighting.” Ibn Abbas said: “This is the first Verse that was revealed concerning fighting.”

أَخْبَرَنَا عَبْدُ الرَّحْمَنِ بْنُ مُحَمَّدِ بْنِ سَلاَّمٍ، قَالَ حَدَّثَنَا إِسْحَاقُ الأَزْرَقُ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنِ الأَعْمَشِ، عَنْ مُسْلِمٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ لَمَّا أُخْرِجَ النَّبِيُّ صلى الله عليه وسلم مِنْ مَكَّةَ قَالَ أَبُو بَكْرٍ أَخْرَجُوا نَبِيَّهُمْ إِنَّا لِلَّهِ وَإِنَّا إِلَيْهِ رَاجِعُونَ لَيَهْلِكُنَّ ‏.‏ فَنَزَلَتْ ‏{‏ أُذِنَ لِلَّذِينَ يُقَاتَلُونَ بِأَنَّهُمْ ظُلِمُوا وَإِنَّ اللَّهَ عَلَى نَصْرِهِمْ لَقَدِيرٌ ‏}‏ فَعَرَفْتُ أَنَّهُ سَيَكُونُ قِتَالٌ ‏.‏ قَالَ ابْنُ عَبَّاسٍ فَهِيَ أَوَّلُ آيَةٍ نَزَلَتْ فِي الْقِتَالِ ‏.‏