Kautilya's Arthashastra 13.2.44

13.2.44

siddhapravrajitacaityastūpadaivatapratimānām abhīkṣṇābhigamaneṣu vā bhūmigṛhasuruṅgārūḍhabhittipraviṣṭās tīkṣṇāḥ param abhihanyuḥ //

When the enemy is in the habit of paying frequent visits to ascetics, altars, sacred pillars (stúpa), and images of gods, spies hidden in underground chambers or in subterranean passages, or inside the walls, may strike him down.