Kautilya's Arthashastra 7.18.41

7.18.41

mitravyasanato vārir uttiṣṭhed yo 'navagrahaḥ /
mitreṇaiva bhavet sādhyaś chāditavyasanena saḥ //
amitravyasanān mitram utthitaṃ yad virajyati /
arivyasanasiddhyā tatśatruṇaiva prasidhyati //

When an enemy furiously rises against his own enemy (i.e., the conqueror's friend) under troubles, the former should be put down by the latter himself with troubles concealed.

When a friend keeps quiet after rising against an enemy under troubles, that friend will be subdued by the enemy himself after getting rid of his troubles.