Bhagavad Gita 5.21

बाह्यस्पर्शेष्वसक्तात्मा विन्दत्यात्मनि यत्सुखम् |
स ब्रह्मयोगयुक्तात्मा सुखमक्षयमश्नुते

Translation

Those who are not attached to external sense pleasures realize divine bliss in the self. Being united with God through Yog, they experience unending happiness.