Deuteronomy 19:3

1 When Jehovah thy God shall cut off the nations, whose land Jehovah thy God giveth thee, and thou succeedest them, and dwellest in their cities, and in their houses;

2 thou shalt set apart three cities for thee in the midst of thy land, which Jehovah thy God giveth thee to possess it.

3 Thou shalt prepare thee the way, and divide the borders of thy land, which Jehovah thy God causeth thee to inherit, into three parts, that every manslayer may flee thither.

4 And this is the case of the manslayer, that shall flee thither and live: whoso killeth his neighbor unawares, and hated him not in time past;

5 as when a man goeth into the forest with his neighbor 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 neighbor, so that he dieth; he shall flee unto one of these cities and live:

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

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