Numbers 35:28 WEB

²⁶  But if the manslayer shall at any time go beyond the border of his city of refuge, where he flees,

²⁷  and the avenger of blood find him outside of the border of his city of refuge, and the avenger of blood kill the manslayer; he shall not be guilty of blood,

²⁸  because he should have remained in his city of refuge until the death of the high priest: but after the death of the high priest the manslayer shall return into the land of his possession.

²⁹  These things shall be for a statute [and] ordinance to you throughout your generations in all your dwellings.

³⁰  Whoever kills any person, the murderer shall be slain at the mouth of witnesses: but one witness shall not testify against any person that he die.