भीष्मविक्रमदर्शनं तथा क्रौञ्चारुणव्यूहविधानम् | Bhīṣma’s Ascendancy and the Organization of the Krauñcāruṇa Formation
अधर्म धर्ममिति या मन्यते तमसा5<वृता | सर्वार्थान् विपरीतांश्व बुद्धि: सा पार्थ तामसी
adharmaṁ dharmam iti yā manyate tamasāvṛtā | sarvārthān viparītāṁś ca buddhiḥ sā pārtha tāmasī ||
Arjuna sprach: Jener Intellekt (buddhi), der, von Dunkelheit (tamas) verhüllt, das Unrechte für das Rechte hält und ebenso alle Dinge verkehrt auffasst—ein solcher Intellekt, o Pārtha, wird tamasisch (tāmasī) genannt.
अजुन उवाच
An intellect dominated by tamas loses moral and practical discernment: it labels adharma as dharma and habitually interprets matters in a distorted, opposite way. Such confusion is the mark of a tāmasī buddhi.
In the Bhīṣma Parva’s Bhagavadgītā discourse, Kṛṣṇa is classifying intellect (buddhi) according to the three guṇas. Here he defines the tamasic type by its darkness-born misjudgment—especially the inversion of dharma and adharma—addressing Arjuna as Pārtha.