(5) باب إِثْمِ مَنْ قَتَلَ مُعَاهَدًا بِغَيْرِ جُرْمٍ
Narrated `Abdullah bin `Amr:
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."
Reference: Sahih al-Bukhari 3166
In-book reference: Book 58, Hadith 8
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 4, Book 53, Hadith 391