Deuteronomy 19:2-4

Evangelical Heritage Version

² set aside three cities within the land that the Lord your God is giving you to possess. ³ Prepare roads^[a] for yourselves, and divide the land that the Lord your God is giving you as an inheritance into three parts, so that anyone who has killed a person will be able to flee to one of these cities.

⁴ Now this is an example of a person who has killed someone who may flee there and live: someone who has struck down his friend unintentionally, without being hateful toward him beforehand.