Allah's Apostle ﷺ 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.  

قَالَ رَسُولُ اللَّهِ ﷺ لاَ تُقْتَلُ نَفْسٌ ظُلْمًا إِلاَّ كَانَ عَلَى ابْنِ آدَمَ الأَوَّلِ كِفْلٌ مِنْ دَمِهَا لأَنَّهُ كَانَ أَوَّلَ مَنْ سَنَّ الْقَتْلَ  

This hadith has been narrated on the authority of Jarir and 'Isa b. Yunus with a slight variation of words.  

لأَنَّهُ سَنَّ الْقَتْلَ لَمْ يَذْكُرَا أَوَّلَ