Bhagavad Gita Chapter 18, Verse 29

बुद्धेर्भेदं धृतेश्चैव गुणतस्त्रिविधं शृणु | प्रोच्यमानमशेषेण पृथक्त्वेन धनञ्जय ||

buddher bhedaṁ dhṛteś caiva guṇatas trividhaṁ śṛṇu procyamānam aśeṣeṇa pṛthaktvena dhanañjaya

O Arjuna, hear the three kinds of distinction of intellect and firmness according to gunas, being explained completely and distinctly.

Krishna introduces the teaching about the three kinds of intellect and firmness according to gunas. 'Buddher bhedaṁ dhṛteś caiva guṇatas trividhaṁ śṛṇu'—hear (śṛṇu) the three kinds (trividham) of distinction (bhedam) of intellect (buddheḥ) and firmness (dhṛteḥ) according to gunas (guṇataḥ). 'Procyamānam aśeṣeṇa pṛthaktvena dhanañjaya'—being explained (procyamānam) completely (aśeṣeṇa) and distinctly (pṛthaktvena), O Arjuna (dhanañjaya). This sets up the detailed teaching about how intellect and firmness are classified according to the three gunas: sattvic, rajasic, and tamasic. Understanding this helps you recognize the quality of your intellect and firmness, and how to align with sattvic qualities. This comprehensive classification continues the teaching about everything being classified by gunas.