Mahabharata 12.86.32

12.86.32

viśvāsayetparāṃścaiva viśvasenna tu kasyacit |
putreṣvapi hi rājendra viśvāso na praśasyate || 32 ||

The aid-de-camp of the king that protects his person should be endued with similar qualities. The officer also that guards his capital or citadel should possess the same accomplishments. The king's minister should be conversant with the conclusions of the scriptures and competent in directing wars and making treaties. He should, further, be intelligent, possessed of courage, modest, and capable of keeping secrets. He should also be of high birth endued with strength of mind, and pure in conduct. If possessed of these qualities, he should be regarded worthy. The commander of the king's forces should be possessed of similar accomplishments. He should also be conversant with the different kinds of battle array and with the uses of engines and weapons. He should be able to bear exposure to rain, cold, heat, and wind, and watchful of the laches of foes. The king, O monarch, should be able to lull his foes into a sense of security. He should not, however, himself trust anyone. The reposing of confidence on even his own son is not to be approved of. I have now, O sinless one, declared to thee what the conclusions of the scriptures are. Refusal to trust anyone has been said to be one of the highest mysteries of king-craft.'"