Numbers 35:26-28

New Revised Standard Version, Anglicised

²⁶ But if the slayer shall at any time go outside the bounds of the original city of refuge, ²⁷ and is found by the avenger of blood outside the bounds of the city of refuge, and is killed by the avenger, no blood-guilt shall be incurred. ²⁸ For the slayer must remain in the city of refuge until the death of the high priest; but after the death of the high priest the slayer may return home.