Deuteronomy 21:4 "Which shall neither be plowed nor sown"

There are special laws for dealing with an unsolved murder (See Positive Mitzvah 181).

The elders and judges must make a solemn declaration and carry out a detailed procedure at the bank of a stream.

This teaches us the responsibility the community has to protect life and atone for the unsolved murder.

This Negative Mitzvah concerns the land surrounding the stream where this procedure takes place. We are cautioned not to plant or work that soil.