Numbers 35:28-30

New Revised Standard Version, Anglicised Catholic Edition

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.

²⁹ These things shall be a statute and ordinance for you throughout your generations wherever you live.

³⁰ If anyone kills another, the murderer shall be put to death on the evidence of witnesses; but no one shall be put to death on the testimony of a single witness.