Numbers 35:30-34

30‘1If anyone kills a person, the murderer shall be put to death at the 2evidence of witnesses, but 3no person shall be put to death on the testimony of one witness.

31Moreover, you shall not take ransom for the life of a murderer who is guilty of death, but he shall surely be put to death.

32You shall not take ransom for him who has fled to his city of refuge, that he may return to live in the land 4before the death of the priest.

335So you shall not pollute the land in which you are; for blood pollutes the land and no expiation can be made for the land for the blood that is shed on it, except 6by the blood of him who shed it.

34You shall not 7defile the land in which you live, in the midst of which 8I dwell; for I the Lord am dwelling in the midst of the sons of Israel.’”