Numbers 35:11–28 (NIV):
11 select some towns to be your cities of refuge, to which a person who has killed someone accidentally may flee. 12 They will be places of refuge from the avenger, so that anyone accused of murder may not die before they stand trial before the assembly. 15 These six towns will be a place of refuge for Israelites and for foreigners residing among them, so that anyone who has killed another accidentally can flee there.
16 “ ‘If anyone strikes someone a fatal blow with an iron object, that person is a murderer; the murderer is to be put to death. 17 Or if anyone is holding a stone and strikes someone a fatal blow with it, that person is a murderer; the murderer is to be put to death. 18 Or if anyone is holding a wooden object and strikes someone a fatal blow with it, that person is a murderer; the murderer is to be put to death. 19 The avenger of blood shall put the murderer to death; when the avenger comes upon the murderer, the avenger shall put the murderer to death. 20 If anyone with malice aforethought shoves another or throws something at them intentionally so that they die 21 or if out of enmity one person hits another with their fist so that the other dies, that person is to be put to death; that person is a murderer. The avenger of blood shall put the murderer to death when they meet.
22 “ ‘But if without enmity someone suddenly pushes another or throws something at them unintentionally 23 or, without seeing them, drops on them a stone heavy enough to kill them, and they die, then since that other person was not an enemy and no harm was intended, 24 the assembly must judge between the accused and the avenger of blood according to these regulations. 25 The assembly must protect the one accused of murder from the avenger of blood and send the accused back to the city of refuge to which they fled. The accused must stay there until the death of the high priest, who was anointed with the holy oil.