Deuteronomy 19:4-13

4“1Now this is the case of the manslayer who may flee there and live: when he 2kills his friend 3unintentionally, 4not hating him previously-- 5as when a man goes into the forest with his friend to cut wood, and his hand 5swings the axe to cut down the tree, and the iron head slips off the 6handle and 7strikes his friend so that he dies--he may flee to one of these cities and live; 6otherwise the avenger of blood might pursue the manslayer 8in the heat of his anger, and overtake him, because the way is long, and 9take his life, though he was not deserving of death, since he had not hated him previously. 7Therefore, I command you, saying, ‘You shall set aside three cities for yourself.’

8“If the Lord your God 10enlarges your territory, just as He has sworn to your fathers, and gives you all the land which He 11promised to give your fathers-- 9if you 12carefully observe all this commandment which I command you today, 13to love the Lord your God, and to walk in His ways always--14then 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 15bloodguiltiness be on you.

11“But 16if there is a man who hates his neighbor and lies in wait for him and rises up against him and strikes 17him so that he dies, and he flees to one of these cities, 12then the elders of his city shall send and take him from there and deliver him into the hand of the avenger of blood, that he may die. 131819You shall not pity him, but 20you shall purge the blood of the innocent from Israel, that it may go well with you.