Narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: Whoever kills a person from among those with whom there is a treaty, will not smell the fragrance of Paradise, though its fragrance is perceived from a distance of forty years.
Hadith Takhrij«اسناده صحيح۔ أخرجه ابن ماجه: 2686، والنسائي: 8/25، (انظر مسند أحمد ترقيم الرسالة: 6745 ترقیم بيت الأفكار الدولية: 6745»
Brief Explanation
Benefits: … Islam has greatly emphasized the observance of agreements, and in this matter, it has made no distinction between disbeliever and Muslim. If even an ordinary Muslim enters into an agreement with a disbeliever or grants him protection, it becomes obligatory upon all Muslims to fulfill the requirements of that agreement.