Kautilya's Arthashastra 12.4.8

12.4.8

pākvamāṃsikaudanikauṇḍikāpūpikavyañjanā vā paṇyaviśeṣam avaghoṣayitvā parasparasaṃgharṣeṇa kālikaṃ samarghataram iti vā parān āhūya rasena svapaṇyāny apacārayeyuḥ //

Spies, disguised as experts in trading in cooked flesh, cooked rice, liquor, and cakes, may vie with each other in proclaiming in public the sale of a fresh supply of their special articles at cheap price and may sell the articles mixed with poison to the attracted customers of the enemy.