tad-buddhayas tad-ātmānas
tan-niṣṭhās tat-parāyaṇāḥ
gacchanty apunar-āvṛttiḿ

Translation of Bhagavad Gita 5.17

When one’s intelligence, mind, faith and refuge are all fixed in the Supreme, then one becomes fully cleansed of misgivings through complete knowledge and thus proceeds straight on the path of liberation.

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

The Supreme Transcendental Truth is Lord Krishna. The whole Bhagavad-gita centers around the declaration that Krishna is the Supreme Personality of Godhead. That is the version of all Vedic literature. Para-tattva means the Supreme Reality, who is understood by the knowers of the Supreme as Brahman, Paramatma and Bhagavan. Bhagavan, or the Supreme Personality of Godhead, is the last word in the Absolute. There is nothing more than that. The Lord says, mattah parataram nanyat kincid asti dhananjaya. Impersonal Brahman is also supported by Krishna: brahmano hi pratishthaham. Therefore in all ways Krishna is the Supreme Reality. One whose mind, intelligence, faith and refuge are always in Krishna, or, in other words, one who is fully in Krishna consciousness, is undoubtedly washed clean of all misgivings and is in perfect knowledge in everything concerning transcendence. A Krishna conscious person can thoroughly understand that there is duality (simultaneous identity and individuality) in Krishna, and, equipped with such transcendental knowledge, one can make steady progress on the path of liberation.

Commentary by Sri Vishvanatha Chakravarthi Thakur of Gaudiya Sampradaya:

But this vidya reveals knowledge about the jivatma, not knowledge of the paramatma.

The Lord says, bhaktyaham ekaya grahyah: I am attainable only by bhakti. Therefore the jnanais must additionally practice bhakti in order to obtain knowledge of paramatma. That is stated in this verse.

The word tat refers to the Supreme Lord previously mentioned as vibhu in verse 15. Those who place their intelligence in the Supreme Lord, who are dedicated to contemplation on the Lord using intellect (tad buddhayah), who are meditating on the Lord using the mind (tad atmanah), who fix their knowledge in the Lord, giving up sattvika knowledge of the soul apart from the body, and becoming fixed only in the Lord, (the Lord says one should place knowledge in him (jnanam ca mayi sannyaset), becoming absorbed in the processes of hearing and chanting about the Lord (tat paranayanah) do not attain birth again. As will be said later,

bhaktya mam abhijanati yavan yas casmi tattvatah
tato mam tattvato jnatva visate tad-anantaram

I am to be known in truth only by bhakti. Knowing me in truth, one attains me. BG 18.55

Those persons’ ignorance has been previously completely destroyed by vidya (jnana nirdhuta kalmasah).

Commentary by Sri Ramanuja of Sri Sampradaya:

5.17 ‘Those whose intellects pursue It,’ i.e., those who have determined to have the vision of the self in this way; ‘those whose minds think about It,’ i.e., those whose minds have the self for their aim, those who undergo discipline for It, i.e., those who are devoted to the practices for Its attainment; ‘those who hold It as their highest object,’ i.e., those who consider It as their highest goal — such persons, having their previous impurities cleansed by the knowledge which is practised in this way, attain the self as taught. ‘From that state there is no return’ — the state from which there is no return means the state of the self. The meaning is that they attain the self which rests in Its own nature.

Commentary by Sri Sridhara Swami of Rudra Sampradaya:

Lord Krishna is now stating the results of such worship. Those who are fixed and resolute in this spiritual knowledge, whose conviction is unwavering and steady, whose one aim is that, whose mind is centered in that, whose only refuge is that and that alone. Whose sins have been dissolved by atma tattva or realisation of the soul and by the grace of the atma one achieves moksa or liberation and attains the Supreme Lord.

Commentary by Sri Madhvacharya of Brahma Sampradaya:

Lord Krishna declares the means to attain that supra-conscious awareness that illuminates one’s intelligence and leads directly to moksa or liberation from material existence.

Commentary by Sri Keshava Kashmiri of Kumara Sampradaya:

The question may be raised when does true knowledge of the spiritual reality reveal itself? Lord Krishna describes this beginning with the words tad buddhayas meaning when one’s intelligence is focused in Him and whose sinful reactions have been eradicated by spiritual knowledge. The purport is just as one shrouded in ignorance suffers samsara or the perpetual cycle of birth and death. One who by the strength of mind has perceived the atma or soul within is no longer affected by this transmigratory existence full of all types of evil and is untouched by the characteristics of samsara.

Commentary by Sri Adi Shankaracharya of Advaita Sampradaya:

5.17 Tat-buddhayah, those who have their intellect absorbed in That, [Here Ast. reads ‘tasmin brahmani, in that Brahman’.-Tr.] in the supreme Knowledge which has been revealed; tat-atmanah, whose Self is That, who have That (tat) supreme Brahman Itself as their Self (atma); tat-nisthah, who are steadfast in That-nistha is intentness, exclusive devotion; they are called tat-nisthah who become steadfast only in Brahman by renouncing all actions; and tat-parayanah, who have That as their supreme (para) Goal (ayana), who have That alone as their supreme Resort, i.e. who are devoted only to the Self; those who have got their ignorance destroyed by Knowledge-those who are of this kind-, they gacchanti, attain; apunaravrttim, the state of non-returning, non-association again with a body; jnana-nirdhuta-kalmasah, their dirt having been removed, destroyed, by Knowledge. Those whose dirt (kalmasa), the defect in the form of sin etc., which are the cause of transmigration, have been removed, destryed (nirdhuta), by the aforesaid Knowledge (jnana) are jnana-nirdhuta-kalmasah, i.e. the monks. How do those learned ones, whose ignorance regarding the Self has been destroyed by Knowledge, look upon Reality? That is being stated:

Commentary by Sri Abhinavagupta of Kaula Tantra Sampradaya:

5.17 Because it is only the inherent nature that exerts thus, therefore [the Lord] says that the men, who have destroyed their illusion would remain as follows –

Sanskrit Shloka Without Transliteration Marks:

tad-buddhayas tad-atmanas
tan-nisthas tat-parayanah
gacchanty apunar-avrttim

Sanskrit to English Word for Word Meanings:

tat-buddhayaḥ — those whose intelligence is always in the Supreme; tat-ātmānaḥ — those whose minds are always in the Supreme; tat-niṣṭhāḥ — those whose faith is only meant for the Supreme; tat-parāyaṇāḥ — who have completely taken shelter of Him; gacchanti — go; apunaḥ-āvṛttim — to liberation; jñāna — by knowledge; nirdhūta — cleansed; kalmaṣāḥ — misgivings.