Kautilya's Arthashastra 8.1.53

8.1.53

"daṇḍamitravyasanayor mitravyasanam" iti vātavyādhiḥ //

Vátavyádhi says that of the distress of the army and of an ally, the distress of an ally is more serious--an ally, though he is not fed and is far off, is still serviceable; he drives off not only the rear-enemy and the friends of the rear-enemy, but also the frontal enemy and wild tribes; he also helps his friend with money, army, and lands on occasions of troubles.