The 228th prohibition is that we are forbidden from selling the open areas surrounding the Levitical cities.

The source of this mitzvah is G‑d's statement,1 "Do not sell the open areas surrounding their cities."

You are aware that Scripture2 grants the Levites cities, open areas and fields. The open areas are 1000 amos wide and an additional 2000 amos beyond that are for fields and vine­yards, as explained in tractate Sotah.3 This prohibition forbids the Levites from changing these borders. They may not make the space allotted for a city into an open area; an open area into a city; a field into an open area; an open area into a field. The phrase, "Do not sell" is explained in the Oral Tradition as mean­ing, "Do not change."

The details of this mitzvah are explained in the end of trac­tate Erachin.4