Deuteronomy 19:2 in the King James Version
Thou shalt separate three cities for thee in the midst of thy land, which the LORD thy God giveth thee to possess it.
Context
1 When the LORD your God cuts off the nations whose land the LORD your God gives you, and you succeed them and dwell in their cities and in their houses,
2 you shall set apart three cities for yourselves in the middle of your land, which the LORD your God gives you to possess.
3 You shall prepare the way, and divide the borders of your land which the LORD your God causes you to inherit into three parts, that every man slayer may flee there.