Chapter 4 · verse 38 · gita.yoga.org

Bhagavad Gita 4.38

न हि ज्ञानेन सदृशं पवित्रमिह विद्यते। तत्स्वयं योगसंसिद्धः कालेनात्मनि विन्दति

Verily, there is no purifier in this world like knowledge. He who is perfected in Yoga finds it within the Self in due time.