Parashas Masei · Passuk 35:4 · TT note 1
Chabad.org — English translation + Rashi
Torah Temimah points to Eruvin 57a (TT note on “מִקִּיר הָעִיר וָחוּצָה”).
English: Rabbi Meir says: one gives a karpef (outer margin) to the city. From where is this derived? Rava said: the verse says “from the wall of the city and outward” — the Torah said: give an outer space, and only afterward measure.
Halakhic measurement of the migrash — an outer karpef is allocated before the thousand-cubit measure begins.
The migrash of a thousand cubits begins only after an additional outer margin (karpef) has been set aside from the city wall.