Mura reported from Masruq, from Abdullah, that the Prophet ﷺ said, "No soul is killed unjustly except that a share of its blood falls upon the first son of Adam, for he was the first to establish the practice of killing."
أخبرنا عمرو بن علي عن عبد الرحمن قال حدثنا سفيان عن الأعمش
بن مرة عن مسروق عن عبد الله عن النبي ﷺ قال لا تقتل نفس ظلما إلا كان على ابن آدم الأول كفل من دمها وذلك أنه أول من سن القتل
Bukhari reported it in the Book of the Prophets, the chapter on the creation of Adam and his progeny, no. 3335, from the hadith of Amash. Muslim reported it in the Book of Qasamah, the chapter explaining the sin of the one who initiated killing, no. 1677, from the hadith of Sufyan Thawri, through the same chain. It is also in Al-Kubra, no. 3447.