Sahih al-Bukhari, Volume 8, Book 76, Hadith 500 (USC-MSA) ⓘ

Narrated Sa`d bin Sahl As-Sa`idi: The Prophet looked at a man fighting against the pagans and he was one of the most competent persons fighting on behalf of the Muslims. The Prophet said, "Let him who wants to look at a man from the dwellers of the (Hell) Fire, look at this (man)." Another man followed him and kept on following him till he (the fighter) was injured and, seeking to die quickly, he placed the blade tip of his sword between his breasts and leaned over it till it passed through his shoulders (i.e., committed suicide)." The Prophet added, "A person may do deeds that seem to the people as the deeds of the people of Paradise while in fact, he is from the dwellers of the (Hell) Fire: and similarly a person may do deeds that seem to the people as the deeds of the people of the (Hell) Fire while in fact, he is from the dwellers of Paradise. Verily, the (results of) deeds done, depend upon the last actions."

حَدَّثَنَا عَلِيُّ بْنُ عَيَّاشٍ، حَدَّثَنَا أَبُو غَسَّانَ، قَالَ حَدَّثَنِي أَبُو حَازِمٍ، عَنْ سَهْلِ بْنِ سَعْدٍ السَّاعِدِيِّ، قَالَ نَظَرَ النَّبِيُّ صلى الله عليه وسلم إِلَى رَجُلٍ يُقَاتِلُ الْمُشْرِكِينَ، وَكَانَ مِنْ أَعْظَمِ الْمُسْلِمِينَ غَنَاءً عَنْهُمْ فَقَالَ ‏"‏ مَنْ أَحَبَّ أَنْ يَنْظُرَ إِلَى رَجُلٍ مِنْ أَهْلِ النَّارِ فَلْيَنْظُرْ إِلَى هَذَا ‏"‏‏.‏ فَتَبِعَهُ رَجُلٌ فَلَمْ يَزَلْ عَلَى ذَلِكَ حَتَّى جُرِحَ، فَاسْتَعْجَلَ الْمَوْتَ‏.‏ فَقَالَ بِذُبَابَةِ سَيْفِهِ، فَوَضَعَهُ بَيْنَ ثَدْيَيْهِ، فَتَحَامَلَ عَلَيْهِ، حَتَّى خَرَجَ مِنْ بَيْنِ كَتِفَيْهِ‏.‏ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ إِنَّ الْعَبْدَ لَيَعْمَلُ فِيمَا يَرَى النَّاسُ عَمَلَ أَهْلِ الْجَنَّةِ، وَإِنَّهُ لَمِنْ أَهْلِ النَّارِ، وَيَعْمَلُ فِيمَا يَرَى النَّاسُ عَمَلَ أَهْلِ النَّارِ وَهْوَ مِنْ أَهْلِ الْجَنَّةِ، وَإِنَّمَا الأَعْمَالُ بِخَوَاتِيمِهَا ‏"‏‏.‏