Joshua 20:3

that the manslayer who kills any person accidentally or unintentionally may flee there. They shall be to you for a refuge from the avenger of blood.

Treasury of Scripture Knowledge

Summary

That the slayer that killeth any person unawares and unwittingly may flee thither: and they shall be your refuge from the avenger of blood.

General references

Bible References

General references

Numbers 35:19
The avenger of blood shall himself put the murderer to death: when he meets him, he shall put him to death.