Numbers 35:12-19

12And they shall be to you cities for refuge from the avenger; that the manslayer may not die, until he stand before the congregation in judgment. 13And of these cities which ye shall give six cities shall ye have for refuge. 14Ye shall give three cities on this side of Jordan, and three cities shall ye give in the land of Canaan, which shall be cities of refuge. 15These six cities shall be a refuge, both for the children of Israel, and for the stranger, and for the sojourner among them: that every one that killeth any person unintentionally may flee there. 16And if he shall smite him with an instrument of iron, so that he shall die, he is a murderer: the murderer shall surely be put to death. 17And if he shall smite him by throwing a stone, by which he may die, and he shall die, he is a murderer: the murderer shall surely be put to death.1 18Or if he shall smite him with an hand weapon of wood, by which he may die, and he shall die, he is a murderer: the murderer shall surely be put to death. 19The avenger of blood himself shall slay the murderer: when he meeteth him, he shall slay him.