Numbers 35:22-27

“ ‘But a person might suddenly shove someone, and not from hatred. Or a person might accidentally throw something and hit someone. Or a person might drop a rock on someone he couldn’t see and kill that person. There was no plan to hurt anyone and no hatred for the one who was killed. If that happens, the community must judge between the relative of the dead person and the killer, according to these rules. They must protect the killer from the dead person’s relative, sending the killer back to the original city of safety, to stay there until the high priest dies (the high priest had the holy oil poured on him). “ ‘Such a person must never go outside the limits of the city of safety. If a relative of the dead person finds the killer outside the city, the relative may kill that person and not be guilty of murder.