Deuteronomy 19:9-11

9if you 1carefully observe all this commandment which I command 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 gives you as an inheritance, and 4bloodguiltiness be on you.

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