Kautilya's Arthashastra 7.6.29

7.6.29

jñātvā yathābuddhy avasthāpayitavyaḥ //

When a king thinks that "This renegade supplies me with full information about my enemy's weakness, and, therefore, he deserves to remain here; his own people with me are in friendship with my friends and at enmity with my enemies and are easily excited at the sight of greedy and cruel persons or of a band of enemies," he may treat such a renegade as deserved.