Numbers 35:22-25

22“But if anyone suddenly pushes a person without hostility or throws any object at him without malicious intent

23or without looking drops a stone that could kill a person and he dies, but he was not his enemy and didn’t intend to harm him,

24the assembly is to judge between the person who kills someone and the avenger of blood according to these ordinances.

25The assembly is to protect the one who kills someone from the avenger of blood. Then the assembly will return him to the city of refuge he fled to, and he must live there until the death of the high priest who was anointed with the holy oil.