Kautilya's Arthashastra 9.5.4

9.5.4

yatra bāhyā abhyantarānupajapanti, abhyantarā vā bāhyān, tatrobhayayoge pratijapataḥ siddhir viśeṣavatī //

Where foreigners carry on an intrigue with local men or local men with foreigners, there the consequence of the intrigue carried on by the combination of local and foreign persons will be very serious. Abettors of an intrigue have a better chance of success than its originators; for when the originators of an intrigue are put down, others will hardly succeed in undertaking any other intrigue. Foreigners can hardly win over local persons by intrigue; nor can local men seduce foreigners. Foreigners will find their vast efforts after all unavailing, and only conducive, to the prosperity of the king (against whom they want to conspire).