Deuteronomy 19:9-11

9if you 1carefully follow all of this commandment which I am commanding you today, 2to love the Lord your God, and to walk in His ways always--3then you shall add three more cities for yourself, besides these three. 10So innocent blood will not be shed in the midst of your land which the Lord your God is giving you as an inheritance, and 4guilt for bloodshed will not be on you.

11“But 5if there is a person who hates his neighbor, and waits in ambush for him and rises up against him and strikes 6him so that he dies, and he flees to one of these cities,