Numbers 35:12

The revenger of blood himself shall slay the murderer: when he meeteth him, he shall slay him. But if he thrust him of hatred, or hurl at him by laying of wait, that he die; Or in enmity smite him with his hand, that he die: he that smote him shall surely be put to death; for he is a murderer: the revenger of blood shall slay the murderer, when he meeteth him. But if he thrust him suddenly without enmity, or have cast upon him any thing without laying of wait, Or with any stone, wherewith a man may die, seeing him not, and cast it upon him, that he die, and was not his enemy, neither sought his harm: Then the congregation shall judge between the slayer and the revenger of blood according to these judgments: And the congregation shall deliver the slayer out of the hand of the revenger of blood, and the congregation shall restore him to the city of his refuge, whither he was fled: and he shall abide in it unto the death of the high priest, which was anointed with the holy oil. But if the slayer shall at any time come without the border of the city of his refuge, whither he was fled; And the revenger of blood find him without the borders of the city of his refuge, and the revenger of blood kill the slayer; he shall not be guilty of blood:

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.

That the slayer that killeth any person unawares and unwittingly may flee thither: and they shall be your refuge from the avenger of blood. And when he that doth flee unto one of those cities shall stand at the entering of the gate of the city, and shall declare his cause in the ears of the elders of that city, they shall take him into the city unto them, and give him a place, that he may dwell among them. And if the avenger of blood pursue after him, then they shall not deliver the slayer up into his hand; because he smote his neighbor unwittingly, and hated him not beforetime. And he shall dwell in that city, until he stand before the congregation for judgment, and until the death of the high priest that shall be in those days: then shall the slayer return, and come unto his own city, and unto his own house, unto the city from whence he fled.

And, behold, the whole family is risen against thine handmaid, and they said, Deliver him that smote his brother, that we may kill him, for the life of his brother whom he slew; and we will destroy the heir also: and so they shall quench my coal which is left, and shall not leave to my husband neither name nor remainder upon the earth.