Kautilya's Arthashastra 7.8.25

7.8.25

madhyamodāsīnayor balāṃśadāne yaḥ śūraṃ kṛtāstraṃ duḥkhasaham anuraktaṃ vā daṇḍaṃ dadāti so 'tisaṃdhīyate //

In case of helping with a portion of the army one of the two, a Madhyama or a neutral king, whoever happens to help one who is brave, skillful in handling weapons, and possessed of endurance and friendly feelings will himself be deceived while his enemy, helping one of reverse character, will overreach him.