The Decapitated Calf
"If one is found slain in the land"—Deuteronomy 21:1.
If the corpse of a murdered individual is found lying in the field, and the killer remains unknown, the courts must decapitate a calf [as per the procedure described in the Book of Deuteronomy].
Working the Land near "the Stream of the Decapitated Calf"
"Which shall neither be plowed nor sown"—Deuteronomy 21:4.
It is forbidden to sow or otherwise work the land [surrounding] the stream upon which the calf was decapitated.
Removing Hazards
"You shall not bring blood upon your house"—Deuteronomy 22:8.
We must not leave unattended hazards and pitfalls in our cities and homes.
Removing Sources of Danger from our Property
"You shall place a guard-rail around your roof"—Deuteronomy 22:8.
We are commanded to remove all dangers and hazards from our property. This includes constructing protective guard-rails on the perimeters of roofs and wells, so that no one falls from them or in them. The same applies to all areas of potential danger—we must fix them so that they don't pose any danger.