Deuteronomy 19:6 WEB

⁴  This is the case of the manslayer, that shall flee there and live: whoever kills his neighbor unawares, and didn't hate him in time past;

⁵  as when a man goes into the forest with his neighbor to hew wood, and his hand fetches a stroke with the axe to cut down the tree, and the head slips from the handle, and lights on his neighbor, so that he dies; he shall flee to 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 strike him mortally; whereas he was not worthy of death, inasmuch as he didn't hate him in time past.

⁷  Therefore I command you, saying, You shall set apart three cities for you.

⁸  If Yahweh your God enlarge your border, as he has sworn to your fathers, and give you all the land which he promised to give to your fathers;