Deuteronomy 19:6

2Thou shalt separate three cities for thee in the midst of thy land, which the Lord thy God giveth thee to possess it.

3Thou shalt prepare thee a way, and divide the coasts of thy land, which the Lord thy God giveth thee to inherit, into three parts, that every slayer may flee thither.

4And this is the case of the slayer, which shall flee thither, that he may live: Whoso killeth his neighbour ignorantly, whom he hated not in time past;

5As when a man goeth into the wood with his neighbour to hew wood, and his hand fetcheth a stroke with the axe to cut down the tree, and the head slippeth from the helve, and lighteth upon his neighbour, that he die; he shall flee unto one of those cities, and live:

6Lest the avenger of the blood pursue the slayer, while his heart is hot, and overtake him, because the way is long, and slay him; whereas he was not worthy of death, inasmuch as he hated him not in time past.

7Wherefore I command thee, saying, Thou shalt separate three cities for thee.

8And if the Lord thy God enlarge thy coast, as he hath sworn unto thy fathers, and give thee all the land which he promised to give unto thy fathers;

9If thou shalt keep all these commandments to do them, which I command thee this day, to love the Lord thy God, and to walk ever in his ways; then shalt thou add three cities more for thee, beside these three:

10That innocent blood be not shed in thy land, which the Lord thy God giveth thee for an inheritance, and so blood be upon thee.