Deuteronomy 19:5-7

Modern English Version

⁵ like when a man goes into the forest with his neighbor to cut wood, and his hand raises the axe to cut down the tree, and the axe head slips from the handle and lands on his neighbor causing him to die, then he may flee to one of those cities, and live. ⁶ Otherwise the avenger of blood might, while he is angry, pursue the manslayer and overtake him (because the way is long) and kill him, even though he was not worthy of death (since he did not hate him previously). ⁷ Therefore, I command you, saying, “You shall set apart three cities for yourselves.”