Numbers 35:14-16

New Revised Standard Version, Anglicised Catholic Edition

¹⁴ you shall designate three cities beyond the Jordan, and three cities in the land of Canaan, to be cities of refuge. ¹⁵ These six cities shall serve as refuge for the Israelites, for the resident or transient alien among them, so that anyone who kills a person without intent may flee there.

Concerning Murder and Blood-Revenge

¹⁶ But anyone who strikes another with an iron object, and death ensues, is a murderer; the murderer shall be put to death.