Joshua 20:3

20:3 Anyone who accidentally kills someone can escape there; these cities will be a place of asylum from the avenger of blood.

Joshua 20:5-6

20:5 When the avenger of blood comes after him, they must not hand over to him the one who committed manslaughter, for he accidentally killed his fellow man without premeditation. 20:6 He must remain in that city until his case is decided by the assembly and the high priest dies. Then the one who committed manslaughter may return home to the city from which he escaped.”