Brahma Purana 240.14

Brahmapurāṇa 240.14

tamaś cāṣṭaguṇaṃ jñātvā buddhiṃ saptaguṇāṃ tathā
ṣaḍguṇaṃ ca nabho jñātvā tamaś ca triguṇaṃ mahat //