The LORD spoke to Joshua:
References for Joshua 20:1
"Say to the Israelites, ‘Set up refuge cities for yourselves. I spoke to you about these through Moses.
Anyone who kills by striking down someone unintentionally or by mistake may flee there. These places will be a refuge for you from any member of the victim's family seeking revenge.
The killer will flee to one of these cities, stand at the entrance of the city gate, and explain their situation to the elders of that city. The elders are to let the killer into the city and provide a place of refuge for the killer to live with them.
If a member of the victim's family follows, seeking revenge, they won't hand the killer over. This is because the killer struck down the neighbor by accident and hadn't been an enemy in the past.
The killer will live in that city until there can be a trial before the community or until the death of the one who is high priest at that time. Then the killer may return home, back to the city from which the flight began.'"
References for Joshua 20:6
So they set apart Kedesh in Galilee in the highlands of Naphtali, Shechem in the highlands of Ephraim, and Kiriath-arba (that is, Hebron) in the highlands of Judah.
On the other side of the Jordan east of Jericho, they set up Bezer in the wasteland on the plateau from the tribe of Reuben, Ramoth in Gilead from the tribe of Gad, and Golan in Bashan from the tribe of Manasseh.
These cities were the ones designated for all the Israelites and for immigrants residing among them. Anyone who struck down a person by mistake could flee there and escape death at the hand of some member of the victim's family seeking revenge, until there could be a trial before the community.