Numbers 35:12-19

12The cities shall be for you a refuge from the avenger, that the manslayer may not die until he stands before the congregation for judgment.

13And the cities that you give shall be your six cities of refuge.

14You shall give three cities beyond the Jordan, and three cities in the land of Canaan, to be cities of refuge.

15These six cities shall be for refuge for the people of Israel, and for the stranger and for the sojourner among them, that anyone who kills any person without intent may flee there.

16"But if he struck him down with an iron object, so that he died, he is a murderer. The murderer shall be put to death.

17And if he struck him down with a stone tool that could cause death, and he died, he is a murderer. The murderer shall be put to death.

18Or if he struck him down with a wooden tool that could cause death, and he died, he is a murderer. The murderer shall be put to death.

19The avenger of blood shall himself put the murderer to death; when he meets him, he shall put him to death.