Deuteronomy 19:2–9

²you are to set apart three cities for yourselves within the land the Lord your God is giving you to possess.^{o 3}You are to determine the distances^A and divide the land the Lord your God is granting you as an inheritance into three regions, so that anyone who commits manslaughter can flee to these cities.^B

⁴“Here is the law concerning a case of someone who kills a person and flees there to save his life, having killed his neighbor accidentally without previously hating him: ⁵If, for example, he goes into the forest with his neighbor to cut timber, and his hand swings the ax to chop down a tree, but the blade flies off the handle and strikes his neighbor so that he dies, that person may flee to one of these cities and live. ⁶Otherwise, the avenger of blood in the heat of his anger^C might pursue the one who committed manslaughter, overtake him because the distance is great, and strike him dead. Yet he did not deserve to die,^D since he did not previously hate his neighbor. ⁷This is why I am commanding you to set apart three cities for yourselves. ⁸If the Lord your God enlarges your territory as he swore to your ancestors, and gives you all the land he promised to give them—⁹provided you keep every one of these commands I am giving you today and follow them, loving the Lord your God and walking in his ways at all times—you are to add three more cities to these three.