Bhagavad Gita Chapter 14, Verse 5

सत्त्वं रजस्तम इति गुणाः प्रकृतिसम्भवाः | निबध्नन्ति महाबाहो देहे देहिनमव्ययम् ||

sattvaṁ rajas tama iti guṇāḥ prakṛti-sambhavāḥ nibadhnanti mahā-bāho dehe dehinam avyayam

O mighty-armed one, the three modes—sattva (goodness), rajas (passion), and tamas (ignorance)—born from material nature, bind the eternal soul in the body.

Krishna introduces the three gunas explicitly: 'Sattvaṁ rajas tama iti guṇāḥ'—sattva (goodness), rajas (passion), and tamas (ignorance), these are the three gunas. 'Prakṛti-sambhavāḥ'—born from material nature. 'Nibadhnanti mahā-bāho dehe dehinam avyayam'—they bind (nibadhnanti) the eternal soul (dehinam avyayam) in the body (dehe). This is the key teaching: the three gunas, which are qualities of material nature, bind the eternal soul to the material body. Understanding this is crucial: you, the eternal soul, are being bound by the three gunas. They influence your thoughts, actions, and experiences. They keep you attached to material existence. The rest of the chapter will explain how each guna works and how to transcend them all.