Deuteronomy 19:1-2

1The Lord your God will destroy the nations who now live in the land that he is giving to you. You will chase them out and you will live in their cities and in their houses.

2Make the land into three separate regions. Then choose three special cities, one city in each region. Build good roads to each city so that people can easily travel to them. Then anyone who kills a person can run to one of these cities to be safe.