Kautilya's Arthashastra 7.6.36

7.6.36

paṇyaṃ kuryād asiddhaṃ vā siddhaṃ vā tena saṃvṛtam //
tasyaiva doṣeṇādūṣya parasaṃdheyakāraṇāt //

Or, he may be employed to carry on a secret trade in new or old commodities in foreign countries and may accordingly be accused of conspiracy with the enemy.