Bhagavad Gītā Chapter 17, Verse 23: Krishna to Arjuna — Śraddhātraya-Vibhāga-Yoga

Bhāṣyakāra purports

• Śaṅkaraadvaita

  The three-syllable designation 'om tat sat' — each member a name of Brahman as understood by the knowers of Vedanta — is here praised not as mantra-magic but as a pointer toward nirguna Brahman, which cannot otherwise be indicated. Brahman admits no qualification; these three names converge on what remains when all attributes fall away. That Brahma, the Vedas, and yajnas were 'ordained of old' by means of this designation is stated to glorify the designation's authority, not to imply Brahman is their personal creator.

  divergence: Shankara: 'trividho namanirdeshab brahmanah smrtah vedanteshu brahmavidbhih ... nirdeshastutayartham ucyate' — the statement of past ordaining is eulogy of the designation.

• Rāmānujaviśiṣṭādvaita

  The three terms are not interchangeable synonyms but three distinct modes of relating to Brahman-as-Bhagavan: 'om' marks the ritual act as belonging to the Lord at its very outset; 'tat' points to the Brahman who is the telos of all Vedic action; 'sat' attests that the act has reality and goodness in proportion to its connection with him. Brahmanas, Vedas, and yajnas were fashioned by the Lord himself 'of old,' so these three words woven into every rite seal the practitioner's kainkarya (service-relation) to him.

  divergence: Ramanuja: 'tat sat iti shabbdayor anvayah pujyatvaya vacaktataya ... pura maya eva nirmita ityarthah' — the Lord is the one who ordained them, so the three names affirm his lordship over every rite.

• Madhvadvaita

  These three names belong to the Supreme Brahman alone — Hari, who is eternally distinct from every jiva and from the world. Madhva cites the Rigveda-khilas: 'He in whom the universe is woven, who is himself complete, described truly by the Vedas — him they call tat sat.' The 'sat' of the Chandogya ('sadeva somya idam agra asit') and the 'om' of the Taittiriya are not just speech-sounds but real name-forms of Hari by which ritual becomes self-worship of the Lord. Jivas use these names in rites only as deputies performing the Lord's own worship.

  divergence: Madhva cites Rigveda-khilas directly: 'sarvaishhubhais cabhiyuto na canyaih tatsad ity enam ato vadanti' — these are genuine names of Hari, not arbitrary symbols.

• Vallabhaśuddhādvaita

  Vallabha reads the verse as supremely practical: wherever sacred action (yajna, tapa, dana) lacks the proper desho-kala-sampatti (correct place-time-circumstance), the utterance of these three names supplies what is absent, because they designate Purushottama himself. 'Om' functions as the Pranava that consecrates every rite from the outset; 'tat' points to the inexpressible fullness; 'sat' marks right-conduct as Krsna's own self-expression. That Brahmanas recite, Vedas specify, and yajnas embody these three designations means each element of ritual is an act of Krsna's own will, not a human achievement.

  divergence: Vallabha: 'deshakaladisampattayabhave api tatsampattiprakaram aha ... purna-bhava-prayojaka-shaktya bhavati' — the three names supply completeness when ritual circumstance is lacking.

• Śrīdharabhakti

  Sridhara's concern is pastoral: even a person whose yajnas and tapas are technically flawed need not despair, because the triple name can confer the quality of sattva on an otherwise rajasic or tamasic act. 'Om' is Brahman's name by the sruti 'om iti brahma'; 'tat' designates what lies beyond words; 'sat' captures both reality and goodness, echoing 'sadeva somya idam agra asit.' The fact that Brahma-the-Creator formed Brahmanas, Vedas, and yajnas through this designation shows the names are not later convention but the very medium of creation — and thus powerful enough to purify.

  divergence: Sridhara: 'ayam trividho api namanidesho vigunam api sagunikartum samarthah' — this triple name is capable of conferring sattva-quality even on what is deficient.

• Madhusūdanaadvaita-bhakti

  Madhusudana reads the verse as Krsna's gift of a 'general prayaschitta' (general expiation): when ritual acts are performed with inadvertent defects, the utterance of 'om tat sat' — the triple name of the Paramatman — repairs the apurva (unseen merit) that would otherwise be lost. He cites the sruti: 'pramadat kurvatam karma ... smaranad eva tad vishnoh sampurnam syad' — even defective rites become complete by remembering Vishnu. The Advaita note is that Brahman needs no such names for itself; the names are pedagogical scaffolding. The bhakti note is that such scaffolding is Krsna's compassion, not a concession.

  divergence: Madhusudana: 'tadvaigunyapariharay tatsad iti bhagavannamoccharanarrupam samanyaprayashchittam paramkarunikatayopadishati bhagavan' — the Lord teaches this as a compassionate general remedy for ritual defects.