Kautilya's Arthashastra 7.13.41

7.13.41

mitreṇa grāhayet pārṣṇim abhiyukto 'bhiyoginaḥ /
mitramitreṇa cākrandaṃ pārṣṇigrāhān nivārayet //

he should, with his friend's help, hold his rear-enemy at bay; and with the help of his friend's friend, he should prevent his rear-enemy attacking the ákranda (his rear-ally);