Mbh 1.142.9b

Thou shouldst never trust the faithless, nor trust too much those that are faithful, for if those in whom thou confidest prove thy foes, thou art certain to be annihilated. After testing their faithfulness thou shouldst employ spies in thy own kingdom and in the kingdoms of others. Thy spies in foreign kingdoms should be apt deceivers and persons in the garb of ascetics. Thy spies should be placed in gardens, places of amusement, temples and other holy places, drinking halls, streets, and with the (eighteen) tirthas (viz., the minister, the chief priest, the heir-presumptive, the commander-in-chief, the gate-keepers of the court, persons in the inner apartments, the jailor, the chief surveyor, the head of the treasury, the general executant of orders, the chief of the town police, the chief architect, the chief justice, the president of the council, the chief of the punitive department, the commander of the fort, the chief of the arsenal, the chief of the frontier guards, and the keeper of the forests), and in places of sacrifice, near wells, on mountains and in rivers, in forests, and in all places where people congregate. In speech thou shouldst ever be humble, but let thy heart be ever sharp as razor. And when thou art engaged in doing even a very cruel and terrible act, thou shouldst talk with smiles on thy lips. If desirous of prosperity, thou shouldst adopt all arts--humility, oath, conciliation. Worshipping the feet of others by lowering thy head, inspiring hope, and the like. And, a person conversant with the rules of policy is like a tree decked with flowers but bearing no fruit; or, if bearing fruit, these must be at a great height not easily attainable from the ground; and if any of these fruits seem to be ripe care must be taken to make it appear raw. Conducting himself in such a way, he shall never fade. Virtue, wealth and pleasure have both their evil and good effects closely knit together.