Numbers

And he shall dwell in that city, until he stand before the congregation for judgment, and until the death of the high priest that shall be in those days: then shall the slayer return, and come unto his own city, and unto his own house, unto the city from whence he fled.

And this is the case of the slayer, which shall flee thither, that he may live: Whoso killeth his neighbour ignorantly, whom he hated not in time past;

Speak to the children of Israel, saying, Appoint out for you cities of refuge, whereof I spake unto you by the hand of Moses:

And they shall be unto you cities for refuge from the avenger; that the manslayer die not, until he stand before the congregation in judgment.

He that smiteth a man, so that he die, shall be surely put to death.