Numbers 35:27

23or with any stone, by which a man may die, not seeing him, and cast it on him so that he died, and he was not his enemy and not seeking his harm,

24then the congregation shall judge between the striker and the avenger of blood according to these ordinances.

25The congregation shall deliver the man slayer out of the hand of the avenger of blood, and the congregation shall restore him to his city of refuge, where he had fled. He shall dwell therein until the death of the high priest, who was anointed with the holy oil.

26“‘But if the man slayer shall at any time go beyond the border of his city of refuge where he flees,

27and the avenger of blood finds him outside of the border of his city of refuge, and the avenger of blood kills the man slayer, he shall not be guilty of blood,

28because he should have remained in his city of refuge until the death of the high priest. But after the death of the high priest, the man slayer shall return into the land of his possession.

29“‘These things shall be for a statute and ordinance to you throughout your generations in all your dwellings.

30“‘Whoever kills any person, the murderer shall be slain based on the testimony of witnesses; but one witness shall not testify alone against any person so that he dies.

31“‘Moreover you shall take no ransom for the life of a murderer who is guilty of death. He shall surely be put to death.