Kautilya's Arthashastra 7.18.19

7.18.19

evaṃ svārthaś ca kṛto bhavati madhyamasya priyaṃ ca //

If, among the conqueror's friends who are either reducible or assailable enemies of the madhyama king, some undertake to help the madhyama, then the conqueror should make peace with a third king; and if among the madhyama king's friends who are either reducible or assailable enemies of the conqueror, some are capable of offence and defence and become friendly to the conqueror, then he should make peace with them; thus the conqueror cannot only attain his own ends, but also please the madhyama king.