Numbers 35:19-25

19The avenger of blood himself must kill the murderer; when he meets him, he must kill him.

20“But if he strikes him out of hatred or throws something at him intentionally so that he dies,

21or with enmity he strikes him with his hand and he dies, the one who struck him must surely be put to death, for he is a murderer. The avenger of blood must kill the murderer when he meets him.

22“But if he strikes him suddenly, without enmity, or throws anything at him unintentionally,

23or with any stone large enough that a man could die, without seeing him, and throws it at him, and he dies, even though he was not his enemy nor sought his harm,

24then the community must judge between the slayer and the avenger of blood according to these decisions.

25The community must deliver the slayer out of the hand of the avenger of blood, and the community must restore him to the town of refuge to which he fled, and he must live there until the death of the high priest, who was anointed with the consecrated oil.