Arthashastra
मङ्गल्ये वा ह्रदे तटाक मध्ये वा रात्रौ तेजन तैल अभ्यक्ता नाग रूपिणः शक्ति मुसलान्य् अयोमयानि निष्पेषयन्तस् तथैव ब्रूयुः ॥
Spies, disguised as Nagas (snake-gods and with their body besmeared with burning oil (tejánataila), may stand in the centre of a sacred pool of water or of a lake at night, and sharpening their iron swords or spikes, may shout aloud as before.
english translation
maGgalye vA hrade taTAka madhye vA rAtrau tejana taila abhyaktA nAga rUpiNaH zakti musalAny ayomayAni niSpeSayantas tathaiva brUyuH ॥
hk transliteration by Sanscript