Bhagavad Gita 4.38

न हि ज्ञानेन सदृशं पवित्रमिह विद्यते।
तत्स्वयं योगसंसिद्धः कालेनात्मनि विन्दति।।4.38।।

Na hi gyanena sadrisham pavitramiha vidyate
Tatsvayam yogasansiddhah kalenatmani vindati

Simple meaning, written by AIIn this world there is nothing as purifying as knowledge. One who is perfected in yoga finds it in oneself in due time.

Whole chapter