عن عبد الله بن عمرو رضى الله عنهما عن النبى صلى الله عليه وسلم قال :من قتل معاهدا لم يرح راءحة الجنة وان ريحها توجد من مسيرة اربعين عاما .

صحيح البخارى 

Narrated Abdullah Ibin Amr(May Allah be pleased with them):The Prophet (May the blessings and peace of Allah be upon him) said:Whoever killed a person having treaty with the Muslims,shall not smell the smell of Paradise though its smell is perceived from a distance of forty years.

Sahih Al Bukhari