Kautilya's Arthashastra 12.2.14

12.2.14

kāmavaśān vā siddhavyañjanāḥ sāṃvadanikībhir oṣadhībhir atisaṃdhānāya mukhyeṣu rasaṃ dāpayeyuḥ //

Or to those who have fallen in love, spies, under the guise of ascetics, may administer poison under the plea that the medical drugs given to them are capable of securing the object of love.