The Prophet ﷺ said, "Whoever killed a person having a treaty with the Muslims, shall not smell the smell of Paradise though its smell is perceived from a distance of forty years."  

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ قَتَلَ مُعَاهَدًا لَمْ يَرَحْ رَائِحَةَ الْجَنَّةِ وَإِنَّ رِيحَهَا تُوجَدُ مِنْ مَسِيرَةِ أَرْبَعِينَ عَامًا