Numbers 35:26-28

26But if the manslayer shall in any way come outside the limits of the city of his refuge whither he hath fled,

27and the avenger of blood find him outside the limits of his city of refuge, and the avenger of blood kill the manslayer, there shall be no blood-guiltiness upon him;

28for the manslayer should have remained in the city of his refuge until the death of the high-priest; but after the death of the high-priest he may return into the land of his possession.