Kautilya's Arthashastra 7.18.22

7.18.22

upekṣeta vā "maṇḍalam asya kupyatu svapakṣavadhāt" iti //

If the madhyama king is desirous of securing a would-be friend of the conqueror as a friend, then the conqueror may make peace with another king, or prevent the friend from going to the madhyama, telling him: "It is unworthy of you to forsake a friend who is desirous of your friendship," or the conqueror may keep quiet, if the conqueror thinks that the Circle of States would be enraged against the friend for deserting his own party. If the madhyama king is desirous of securing the conqueror's enemy as his friend, then the conqueror should indirectly (i.e., without being known to the madhyama) help the enemy with wealth and army.