Sahih al-Bukhari 2808
Sahih al-Bukhari · Book 56: Fighting for the Cause of Allah (Jihaad) · Practising good deeds before taking part in a battle
Narrated Al-Bara:
حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ الرَّحِيمِ ، حَدَّثَنَا شَبَابَةُ بْنُ سَوَّارٍ الْفَزَارِيُّ ، حَدَّثَنَا إِسْرَائِيلُ ، عَنْ أَبِي إِسْحَاقَ ، قَالَ سَمِعْتُ الْبَرَاءَ ـ رضى الله عنه ـ يَقُولُ أَتَى النَّبِيَّ صلى الله عليه وسلم رَجُلٌ مُقَنَّعٌ بِالْحَدِيدِ فَقَالَ يَا رَسُولَ اللَّهِ أُقَاتِلُ وَأُسْلِمُ. قَالَ " أَسْلِمْ ثُمَّ قَاتِلْ ". فَأَسْلَمَ ثُمَّ قَاتَلَ، فَقُتِلَ، فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " عَمِلَ قَلِيلاً وَأُجِرَ كَثِيرًا " .
A man whose face was covered with an iron mask (i.e. clad in armor) came to the Prophet (ﷺ) and said, "O Allah's Messenger (ﷺ)! Shall I fight or embrace Islam first? "The Prophet (ﷺ) said, "Embrace Islam first and then fight." So he embraced Islam, and was martyred. Allah's Messenger (ﷺ) said, A Little work, but a great reward. "(He did very little (after embracing Islam), but he will be rewarded in abundance).