Numbers 35:30

27 and the redeemer of blood hath found him at the outside of the border of the city of his refuge, and the redeemer of blood hath slain the man-slayer, blood is not for him;

28 for in the city of his refuge he doth dwell till the death of the chief priest; and after the death of the chief priest doth the man-slayer turn back unto the city of his possession.

29 `And these things have been to you for a statute of judgment to your generations, in all your dwellings:

30 whoso smiteth a person, by the mouth of witnesses doth [one] slay the murderer; and one witness doth not testify against a person -- to die.

31 `And ye take no atonement for the life of a murderer who [is] condemned -- to die, for he is certainly put to death;

32 and ye take no atonement for him to flee unto the city of his refuge, to turn back to dwell in the land, until the death of the priest.

33 `And ye profane not the land which ye [are] in, for blood profaneth the land; as to the land, it is not pardoned for blood which is shed in it except by the blood of him who sheddeth it;