Rashi on Numbers 35:4/רש"י על במדבר ל״ה:ד׳

1אלף אמה סביב A THOUSAND CUBITS ROUND ABOUT — But afterwards, (v. 5) it says, “two thousand cubits”!? How can that be? They assign two thousand for them (for the Levites) round about their cities, and of these, the innermost thousand serves as the “open space” and the outermost is for fields and vineyards (Sotah 27b).