Chapter 5 · verse 21 · gita.yoga.org

Bhagavad Gita 5.21

बाह्यस्पर्शेष्वसक्तात्मा विन्दत्यात्मनि यत्सुखम्। स ब्रह्मयोगयुक्तात्मा सुखमक्षयमश्नुते

With the self unattached to external contacts, he finds happiness in the Self; with the self engaged in the meditation of Brahman, he attains endless happiness.