Exodus 21:12-14 New Revised Standard Version (NRSV)
The Law concerning Violence
12 Whoever strikes a person mortally shall be put to death. 13 If it was not premeditated, but came about by an act of God, then I will appoint for you a place to which the killer may flee. 14 But if someone willfully attacks and kills another by treachery, you shall take the killer from my altar for execution.