Bhagavad Gita 5.21 Chapter 5, Verse 21

बाह्यस्पर्शेष्वसक्तात्मा विन्दत्यात्मनि यत्सुखम् ।
स ब्रह्मयोगयुक्तात्मा सुखमक्षयमश्नुते ॥५.२१॥

bāhyasparśeṣvasaktātmā vindatyātmani yatsukham
sa brahmayogayuktātmā sukhamakṣayamaśnute

Meaning

Unattached to external contacts, one finds happiness within; united with Brahman through yoga, such a person enjoys imperishable joy.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 5.21 (Chapter 5, The Yoga of Renunciation (Karma Sannyasa Yoga), Verse 21)