na hi jñānena sadṛśaḿ
pavitram iha vidyate
tat svayaḿ yoga-saḿsiddhaḥ
kālenātmani vindati

Translation of Bhagavad Gita 4.38

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.

Commentary by Sri A.C. Bhaktivedanta Swami Prabhupada of Gaudiya Sampradaya:

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.

Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

In this world, among those who engage in austerities, yoga other processes, there is nothing to compare to knowledge. That knowledge is not easily attained by everyone, but is fully attained (sam siddhah) by practicing niskama karma yoga. lt is not unobtainable, but is attained in time, not immediately. That knowledge is attained spontaneously within the self (atmani), not by accepting external sannyasa.

Commentary by Sri Ramanuja of Sri Sampradaya:

4.38 Nothing here in this world purifies like this knowledge; for the knowledge of the self destroys all evil. He who has reached perfection by practising Karma Yoga in its form of knowledge daily in the manner taught, in due time, of his own accord, attaints it, i.e., knowledge concerning his own self. Sri Krsna expounds the same lucidly thus:

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

The reason for this conclusion is being given by Lord Krishna and that is amongst all penance’s and austerities and various types of yagnas or offerings of worship there is indeed nothing so purifying that compares with spiritual knowledge. If this is so then why is not everyone striving for the attainment of atma tattva or soul realisation. This will be answered in the next verse. Spiritual knowledge manifests automatically without effort after continuous practice of karma yoga or the following of prescribed Vedic activities has been perfected and not before will one become qualified.

Commentary by Sri Madhvacharya of Brahma Sampradaya:

Lord Krishna praises the value of spiritual wisdom in this verse and the next two. In this process what is the role of the Supreme Lord? Is He simply monitoring every activity from His position as paramatma or the supersoul within all living entities. To the contrary, it is the Supreme Lord who illuminates the consciousness of the living entities over and over again and gives them the opportunity to learn about the ultimate truth.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

In this world nothing is as purifying as spiritual knowledge. Then why is not everyone pursuing this? Lord Krishna explains that first one must become qualified from prolonged practice of karma yoga or prescribed Vedic activities performed without desire for rewards. Then in due course of time if there is no interruption knowledge will arise leading to purity of heart after which atma tattva or soul realisation will be achieved.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

4.38 Hi, indeed; na vidyate, there is nothing; pavitram, purifying, sanctifying; iha, here; sadrsam, comparable; jnanena, to Knowledge. Yoga-samsiddhah, one who has become perfected, who as attained fitness through yoga-the seeker after Liberation who has become samsiddhah, purified, qualified; yogena, through the yoga of Karma and the yoga of concentration-; kalena, after a long time; vindati, realizes, i.e. attains; tat, That, Knowledge; verily svayam, by himself; atmani, in his own heart. That means by which Knowledge is invariably attained is being taught:

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

4.38 Na hi etc. There exists no purifier similar to the knowledge. The purity of other things is due to the touch of Consciousness and is not intrinsic. This point is not elaborated here for fear of a lengthy discussion. This purifying nature of the knowledge, one would understand for himself on reaching the stage of being perfectly enlightened.

Sanskrit Shloka Without Transliteration Marks:

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

Sanskrit to English Word for Word Meanings:

na — nothing; hi — certainly; jñānena — with knowledge; sadṛśam — in comparison; pavitram — sanctified; iha — in this world; vidyate — exists; tat — that; svayam — himself; yoga — in devotion; saḿsiddhaḥ — he who is mature; kālena — in course of time; ātmani — in himself; vindati — enjoys.