For there is no purifier in this world equal to knowledge (jñāna); He who is perfected in discipline (yoga), finds that within the self (ātman) in due time.
No purifier equals knowledge, and in time the man of perfect discipline discovers this in his own spirit.
(38) For nothing on earth resembles wisdom in its power to purify; and this in time a man himself may find within [him]self—a man perfected in spiritual exercise.
4.38 Indeed, there is nothing purifying here comparable to Knowledge. One who has become perfected after a (long) time through yoga, realizes That by himself in his own heart.
4.38 For there is no purifier here equal to knowledge; he that is perfected in Karma Yoga finds this (knowledge) of his own accord in himself in due time.
4.38 Verily, there is no purifier in this world like knowledge. He who is perfected in Yoga finds it in the Self in time.