Numbers 35:25-28

25If the man is a killer but not a murderer, the people must keep him safe from the dead person's relative. They must send him back to the safe city that he ran to. He will live there safely until the death of the leader of God's priests.

26But one day, the killer might go outside the border of the safe city that he ran to.

27If he does that, the dead person's relative might find him outside the safe city. Then, if the dead person's relative kills him, the relative will not be guilty of murder.

28That is because the killer should have stayed in his safe city until the death of the leader of the priests. But after the leader of the priests dies, the killer may return to his own home.