Sahih al-Bukhari, Hadith 6914 ⓘ
Narrated `Abdullah bin `Amr: The Prophet said, "Whoever killed a Mu'ahid (a person who is granted the pledge of protection by the Muslims) shall not smell the fragrance of Paradise though its fragrance can be smelt at a distance of forty years (of traveling).
حَدَّثَنَا قَيْسُ بْنُ حَفْصٍ، حَدَّثَنَا عَبْدُ الْوَاحِدِ، حَدَّثَنَا الْحَسَنُ، حَدَّثَنَا مُجَاهِدٌ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " مَنْ قَتَلَ نَفْسًا مُعَاهَدًا لَمْ يَرَحْ رَائِحَةَ الْجَنَّةِ، وَإِنَّ رِيحَهَا يُوجَدُ مِنْ مَسِيرَةِ أَرْبَعِينَ عَامًا " .
also referenced under: Book 87, Hadith 52 (In-Book) & Volume 9, Book 83, Hadith 49 (USC-MSA)