The Messenger of Allah ﷺ said, "No soul is killed unjustly without the first son of Adam bearing a share of the guilt for its blood, because he was the first to establish the practice of killing."
حدثنا هشام بن عمار حدثنا عيسى بن يونس حدثنا الأعمش عن عبد الله بن مرة عن مسروق
قال رسول الله ﷺ لا تقتل نفس ظلما إلا كان على ابن آدم الأول كفل من دمها لأنه أول من سن القتل
Bukhari related it in the Book of Blood Money, in the chapter, "Whoever saves a life," hadith 6867, 7321, 3335, from the hadith of Amash, with the same chain. Muslim related it in the Book of Retaliation and Warfare, in the chapter explaining the sin of the one who introduces killing, hadith 1677, from the hadith of Isa bin Yunus.