Numbers 35
33 Ref So you shall not pollute the land in which you are: for blood, it pollutes the land; and no expiation can be made for the land for the blood that is shed therein, but by the blood of him who shed it.
34 Ref You shall not defile the land which you inhabit, in the midst of which I dwell: for I, Yahweh, dwell in the midst of the children of Israel.