Numbers 35:26-28

ECB(i) 26 But if, at any time, the murderer comes outside the border of the city of his refuge, where he flees; 27 and the redeemer of blood finds him outside the borders of the city of his refuge and the redeemer of blood murders the murderer; he is not guilty of blood: 28 because he was to settle in the city of his refuge until the death of the great priest: but after the death of the great priest the murderer returns to the land of his possession.