हृदयादुद्धृत्याग्नौ प्रक्षिप्तं चिटिचिटायदिन्द्रधनुर्वर्णं वा विषयुक्तं विद्यात्दग्धस्य हृदयमदग्धं दृष्ट्वा वा ॥ कZ_०४.७.१३ ॥
hṛdayād uddhṛtyāgnau prakṣiptaṃ ciṭiciṭāyad indradhanurvarṇaṃ vā viṣayuktaṃ vidyāt dagdhasya hṛdayam adagdhaṃ dṛṣṭvā vā
After removing the heart and throwing it into fire, if it crackles or shows rainbow-like coloration, one should know it is poisoned; likewise, if in a burnt body the heart is seen unburnt.
It provides an inspectable internal organ for a repeatable test, aiming to strengthen proof beyond external symptoms.