The people of Medina were forced to prepare an army (to fight against the people of Sham during the caliphate of ʿAbdullah bin Az-Zubair at Mecca), and I was enlisted in it; Then I met ʿIkrima, the freed slave of Ibn ʿAbbas, and informed him (about it), and he forbade me strongly to do so (i.e. to enlist in that army), and then said, "Ibn ʿAbbas informed me that some Muslim people were with the pagans, increasing the number of the pagans against Messenger of Allah ﷺ. An arrow used to be shot which would hit one of them (the Muslims in the company of the pagans) and kill him, or he would be struck and killed (with a sword)." Then Allah revealed:-- "Verily! as for those whom the angels take (in death) while they are wronging themselves (by staying among the disbelievers)" (4.97) Abu AlAswad also narrated it.  

أَنَّ نَاسًا مِنَ الْمُسْلِمِينَ كَانُوا مَعَ الْمُشْرِكِينَ يُكَثِّرُونَ سَوَادَ الْمُشْرِكِينَ عَلَى رَسُولِ اللَّهِ ﷺ يَأْتِي السَّهْمُ فَيُرْمَى بِهِ فَيُصِيبُ أَحَدَهُمْ فَيَقْتُلُهُ أَوْ يُضْرَبُ فَيُقْتَلُ فَأَنْزَلَ اللَّهُ {إِنَّ الَّذِينَ تَوَفَّاهُمُ الْمَلاَئِكَةُ ظَالِمِي أَنْفُسِهِمْ} الآيَةَ رَوَاهُ اللَّيْثُ عَنْ أَبِي الأَسْوَدِ  

An army unit was being recruited from the people of Medina and my name was written among them. Then I met ʿIkrima, and when I informed him about it, he discouraged me very strongly and said, "Ibn ʿAbbas told me that there were some Muslims who were with the pagans to increase their number against Messenger of Allah ﷺ (and the Muslim army) so arrows (from the Muslim army) would hit one of them and kill him or a Muslim would strike him (with his sword) and kill him. So Allah revealed:-- 'Verily! As for those whom the angels take (in death) while they are wronging themselves (by staying among the disbelievers).' (4.97)  

قُطِعَ عَلَى أَهْلِ الْمَدِينَةِ بَعْثٌ فَاكْتُتِبْتُ فِيهِ فَلَقِيتُ عِكْرِمَةَ فَأَخْبَرْتُهُ فَنَهَانِي أَشَدَّ النَّهْىِ ثُمَّ قَالَ أَخْبَرَنِي ابْنُ عَبَّاسٍ أَنَّ أُنَاسًا مِنَ الْمُسْلِمِينَ كَانُوا مَعَ الْمُشْرِكِينَ يُكَثِّرُونَ سَوَادَ الْمُشْرِكِينَ عَلَى رَسُولِ اللَّهِ ﷺ فَيَأْتِي السَّهْمُ فَيُرْمَى فَيُصِيبُ أَحَدَهُمْ فَيَقْتُلُهُ أَوْ يَضْرِبُهُ فَيَقْتُلُهُ فَأَنْزَلَ اللَّهُ تَعَالَى {إِنَّ الَّذِينَ تَوَفَّاهُمُ الْمَلاَئِكَةُ ظَالِمِي أَنْفُسِهِمْ}  

[Machine] Some of the Muslims used to be with the polytheists and increase the harm against the Messenger of Allah, ﷺ . They would throw arrows and hit one of them, killing him or causing him injury. So Allah, exalted be He, revealed this verse about them: "Indeed, those whom the angels take [in death] while wronging themselves, [the angels] will say, 'In what [condition] were you?' They will say, 'We were oppressed in the land.' The angels will say, 'Was not the earth of Allah spacious [enough] for you to emigrate therein?' For those, their refuge is Hell - and evil it is as a destination." [Quran 4:97]  

نَاسًا مِنَ الْمُسْلِمِينَ كَانُوا مَعَ الْمُشْرِكِينَ يُكَثِّرُونَ سَوَادَ الْمُشْرِكِينَ عَلَى رَسُولِ اللهِ ﷺ فَيَأْتِي السَّهْمُ يُرْمَى بِهِ فَيُصِيبُ أَحَدَهُمْ فَيَقْتُلُهُ أَوْ يُضْرَبُ فَيُقْتَلُ فَأَنْزَلَ اللهُ تَعَالَى ذِكْرَهُ فِيهِمْ {إِنَّ الَّذِينَ تَوَفَّاهُمُ الْمَلَائِكَةُ ظَالِمِي أَنْفُسِهِمْ قَالُوا فِيمَ كُنْتُمْ قَالُوا كُنَّا مُسْتَضْعَفِينَ فِي الْأَرْضِ قَالُوا أَلَمْ تَكُنْ أَرْضُ اللهِ وَاسِعَةً فَتُهَاجِرُوا فِيهَا فَأُولَئِكَ مَأْوَاهُمْ جَهَنَّمُ وَسَاءَتْ مَصِيرًا} [النساء 97]