I must confess I have not totally read or totally understood the Bible's Books of Law, or Pentateuch. When I do read them, I must remember they come from a time and culture much different from ours.
Part of God's law was how manslaughter was treated. I don't understand that kind of "amazing grace." If one of my "babies" was killed, no matter the circumstances, I'd probably be screaming for blood. But how infinite our God is! And how high his bar of integrity and welcome.
Then the Lord said to Joshua: 2 “Through Moses, I told you to choose some cities to be cities of safety. 3 Anyone who kills someone accidentally can go to a city of safety to hide from the relatives who want to kill him.
Joshua 20:1-3 ERV
The writer of Hebrews didn't say "refuge" or "sanctuary" in his admonition to believers. He did instruct us to show hospitality:
Let love continue among you. 2 Don’t forget to extend your hospitality to all—even to strangers—for as you know, some have unknowingly shown kindness to heavenly messengers in this way. 3 Remember those imprisoned for their beliefs as if you were their cellmate; and care for any who suffer harsh treatment, as you are all one body.
Hebrews 13:1-3 VOICE