Arthashastra
तथा एव भूम्य् एक अन्तरा मित्र प्रकृतिः ॥
The king who is likewise situated close to the enemy, but separated from the conqueror only by the enemy, is termed the friend (of the conqueror).
english translation
tathA eva bhUmy eka antarA mitra prakRtiH ॥
hk transliteration by Sanscript