Numbers 35:11-13, Deuteronomy 19:3-6, Joshua 20:2-6
Speak to the children of Israel, saying, Appoint out for you cities of refuge, whereof I spake unto you by the hand of Moses:
That
the slayer that killeth any person unawares and unwittingly may flee
thither: and they shall be your refuge from the avenger of blood.
And
when he that doth flee unto one of those cities shall stand at the
entering of the gate of the city, and shall declare his cause in the
ears of the elders of that city, they shall take him into the city unto
them, and give him a place, that he may dwell among them.