Sahih Muslim Book 16, Hadith Number 4156.

Chapter : He who sheds the blood first of all bears the burden of all subsequent murders.

‘Abdullah (b. Mas’ud) reported: Allah’s Apostle (may peace be upon him) having said: No person who is killed unjustly, but the share of (this offence of his also) falls upon the first son of Adam, for he was the first to introduce killing.