Bg 4.38

na hi jnanena sadrsam
pavitram iha vidyate
tat svayam yoga-samsiddhah
kalenatmani vindati

Word for word: 
na — nothing; hi — certainly; jnanena — with knowledge; sadrsam — in comparison; pavitram — sanctified; iha — in this world; vidyate — exists; tat — that; svayam — himself; yoga — in devotion; samsiddhah — he who is mature; kalena — in course of time; atmani — in himself; vindati — enjoys.

Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In this world, there is nothing so sublime and pure as transcendental knowledge. Such knowledge is the mature fruit of all mysticism. And one who has become accomplished in the practice of devotional service enjoys this knowledge within himself in due course of time.

Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
When we speak of transcendental knowledge, we do so in terms of spiritual understanding. As such, there is nothing so sublime and pure as transcendental knowledge. Ignorance is the cause of our bondage, and knowledge is the cause of our liberation. This knowledge is the mature fruit of devotional service, and when one is situated in transcendental knowledge, he need not search for peace elsewhere, for he enjoys peace within himself. In other words, this knowledge and peace culminate in Krishna consciousness. That is the last word in the Bhagavad-gita.