Kautilya's Arthashastra 13.2.49

13.2.49

madyabhojanaphelābhis tūryair vābhigatāḥ saha /
prahareyur ariṃ tīkṣṇāḥ pūrvapraṇihitaiḥ saha //E

Or when he is eating or drinking, on these and other occasions, spies, together with other persons previously hidden at those places, may strike him down at the sound of trumpets.