The Book on Government
33/35. Chapter:
Two Men, one of whom kills the other, and both will enter Paradise
Sahih Muslim
حَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، قَالَ هَذَا مَا حَدَّثَنَا أَبُو هُرَيْرَةَ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم فَذَكَرَ أَحَادِيثَ مِنْهَا وَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " يَضْحَكُ اللَّهُ لِرَجُلَيْنِ يَقْتُلُ أَحَدُهُمَا الآخَرَ كِلاَهُمَا يَدْخُلُ الْجَنَّةَ " قَالُوا كَيْفَ يَا رَسُولَ اللَّهِ قَالَ " يُقْتَلُ هَذَا فَيَلِجُ الْجَنَّةَ ثُمَّ يَتُوبُ اللَّهُ عَلَى الآخَرِ فَيَهْدِيهِ إِلَى الإِسْلاَمِ ثُمَّ يُجَاهِدُ فِي سَبِيلِ اللَّهِ فَيُسْتَشْهَدُ " .
It has been reported on the authority of Abu Huraira that the Messenger of Allah (ﷺ) said: God laughs at the two men one of whom kills the other; both of them will enter Paradise. They (the Companions) said: How, Messenger of Allah? He said: One is slain (in the way of Allah) and enters Paradise. Then God forgives the other and guides him to Islam; then he fights in the way of Allah and dies a martyr.
Reference : Sahih Muslim 1890cIn-book reference : Book 33, Hadith 190USC-MSA web (English) reference : Book 20, Hadith 4660