Katha Upanishad Verse 1.3.10

Yama begins to map out the hierarchy of existence, moving from the gross to the subtle. Beyond the physical senses are their objects; beyond objects is the mind; and beyond the mind is the intellect (Buddhi). Further still is the “Mahat” or Great Atman.

Sanskrit Verse

इन्द्रियेभ्यः परा ह्यर्था अर्थेभ्यश्च परं मनः ।
मनसस्तु परा बुद्धिर्बुद्धेरात्मा महान्परः ॥ १० ॥

Transliteration

indriyebhyaḥ parā hyarthā arthebhyaśca paraṃ manaḥ |
manasastu parā buddhirbuddherātmā mahānparaḥ || 10 ||

Translation

Beyond the senses, are the rudiments of its objects; beyond these rudiments is the mind; beyond the mind is atman known as Mahat (great).