Narrated Muhammad bin `Abdur-Rahman Abu Al-Aswad:
The people of Medina were forced to prepare an army (to fight against the people of Sham during the caliphate of `Abdullah bin Az-Zubair at Mecca), and I was enlisted in it; Then I met `Ikrima, the freed slave of Ibn `Abbas, and informed him (about it), and he forbade me strongly to do so (i.e. to enlist in that army), and then said, "Ibn `Abbas informed me that some Muslim people were with the pagans, increasing the number of the pagans against Allah's Messenger (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 Aswad added, "Except the weak ones among men, women,..." (4.98)
USC-MSA web (English) reference: Vol. 6, Book 60, Hadith 120
Arabic reference: Book 65, Hadith 4596