Deuteronomy 19:6-8

King James Version

⁶ Lest 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.

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

⁸ And 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;