Numbers 35:12
You are to have these cities as a refuge from the avenger, so that the manslayer will not die until he stands trial before the assembly.

Numbers 35:14
Select three cities across the Jordan and three in the land of Canaan as cities of refuge.

Joshua 20:9
These are the cities appointed for all the Israelites and foreigners among them, so that anyone who kills a person unintentionally may flee there and not die by the hand of the avenger of blood prior to standing trial before the assembly.