Advaita Vedānta

These commentators read the verse as a practical expiation (prayashchitta) for the inattentive performer. Because sacrifice, austerity, and gift aim at an unseen result, a missing limb could void the fruit; so the Lord teaches uttering 'Om Tat Sat', the name of Brahman the supreme Self, as a general remedy. One source treats the duty to use this name as an implied injunction read into the praise, the way scripture imagines a rule from an established usage, and supports it by the recollection that 'whatever falls away through heedlessness in the rites becomes complete by the mere remembering of Vishnu', and by the conduct of the cultured. The name's power to mend is argued from its being the very instrument by which Prajapati made the brahmins, Vedas, and sacrifices of old.

Śaṅkarācārya · Madhusūdana Sarasvatī · Śrī Nīlakaṇṭha · Dhanapati Sūri · Śrī Ānandagiri

Viśiṣṭādvaita

These commentators stress the differing way each of the three words attaches. 'Om' is connected as a subsidiary used at the very beginning of carrying out Vedic action; 'tat' and 'sat' are connected as designators, used to hold the act worthy of honour. Brahman is identified with the Veda, and by 'Veda' is meant Vedic action, so that sacrifice itself comes to be connected with the word 'sat'. Joined with this threefold word, the brahmins (men of the three classes connected with the Veda), the Vedas, and the sacrifices were of old set forth by the Lord himself ('by Me alone'). One source confirms the traditional reading of the verse as the prayashchitta-formula curing the limb-defect of imperfectly performed sacred acts.

Rāmānujācārya · Vedānta Deśika

Dvaita

These commentators insist 'Brahman' here means the supreme Brahman (Vishnu), not Hiranyagarbha, and 'nirdesha' means a name, not an action, since a name alone can stand in co-reference with 'Om tat sat'. They cite supplementary Rigvedic hymns that 'tat sat' names the One in whom the world is woven and who is himself full, of the very form told in the Veda and without figurative usage, joined with all that is auspicious. A key distinction follows: by 'that Brahman' the Vedic rule is only a manifesting, for the worship of the Self, not a creating; so 'ordained' (vihita) carries two senses, the brahmins being created but the Vedas only made manifest, since the Veda is impersonal and beginningless. One source builds from this that the Veda is of the nature of injunction, injunction needs an independent mandator, and that mandator is the Lord, who works through the beginningless connection of word and meaning, so the Veda's authorlessness is preserved.

Madhvācārya · Śrī Jayatīrtha

Śuddhādvaita

These commentators make this verse the structural and devotional seal of the chapter. 'Om Tat Sat' is the threefold name common to Brahman, the Veda, and the Purushottama (the supreme Person), remembered by both the knowers of Brahman and the devotees (bhaktas). Its special force is that of supplying the missing fitness (sampatti) of place, time, and the rest for any sacrifice, austerity, or gift, even one done without the proper conditions. The Pushtimarga import is devotional: the faith (shraddha) that would otherwise drift through the three gunas is anchored by this triple name in Bhagavan himself, so that an ordinary act of the soul is lifted into grace-yielding worship (pushti). The devotee who utters 'Om Tat Sat' with knowledge of the Lord's own form seals his act into the nirguna circle where the Lord's grace is the sufficient fulfilment.

Vallabhācārya · Śrī Puruṣottama

Kashmir Shaivism

This commentator reads the verse as the way of those whose understanding has crossed beyond the three gunas. Each word does distinct work: 'Om' signals that this meaning of scripture is to be taken up for as long as one has a body; 'tat', a mere pronoun touching only the general and not the particular, teaches the not-aiming-at-a-particular-fruit, so that though Brahman favours every result there is no binding to a specific one; 'sat' (the Real) expresses praise, and marks that a rite done thinking 'this is corrupt' turns tamasic and a rite aimed at a specific fruit is not 'real' since it only binds. Hence acts done with the thought 'this is to be done', without aiming at a fruit, do not bind. He supports this with the Adi-parvan verse that austerity, study, and the natural Vedic rule are no defilement; only being spoilt by the gunas is the defilement (kalka, what binds). In a second, mystical reading the three words name the supreme peace, the freedom of will that touches the universe into awareness, and the fullness that lets the divisions blossom while still full, so the whole array of action stands forth as the natural, unobstructed form, beyond any question of who, what fruit, where, or how.

Ācārya Abhinavagupta

Bhakti

These commentators read the name devotionally and as the means to make deficient action whole. One holds the worry plainly: if every act is more or less rajasic or tamasic the whole undertaking seems vain, so uttering 'Om Tat Sat' upon a karma draws even rajasic or tamasic action into 'sat'. Others say that for the sattvic knowers of Brahman the sacrifices proceed only when preceded by the name of Brahman (named as Vishnu by two of them), so that even with a missing limb the act attains completeness and no defect of fruit remains. The Marathi commentator dwells on the tenderness of naming: Brahman has of itself no name or caste, but the Shruti, out of kindness, gave the formless a token name, as a child answers to the name it is given; the Creator himself gained his power to make the worlds by chanting and pondering these three syllables, then created the brahmins, the Vedas, and the sacrifices. He adds a strong caution that even chanting the name and doing good acts is fruitless without knowing the proper application taught in scripture, like food beside a child who cannot make a meal of it.

Śrīdhara Svāmī · Śrīla Viśvanātha · Śrīla Baladeva · Sant Jñāneśvar

Modern

These commentators keep the practical and devotional sense. One explains that the three words have a divine power of their own: their vibration arouses the latent divinity within and secures the response of the Cosmic Being they name, so that uttering 'Om Tat Sat' (or one of the three) at the start of any sacrifice, study, or meditation removes obstacles and mends a defective rite; the Creator gained his power to create by meditating on this name's meaning. Another reads 'Om Tat Sat' as the very root of the universe from which the first brahmin, the gods, and the sacrifices were made, noting the puzzle that a thing is said to be created 'by a definition' and resolving it (with a cited gloss) as creation from the Parabrahman that the formula defines. A third offers the homely image of the repair-tool: as a cook fixes dough with excess water by adding flour, when a desireless seeker's good act carries a missing limb, taking the name of the Lord from whom the sacrifice itself proceeds sets that deficiency right.

Swami Sivananda · Lokmanya Tilak · Swami Ramsukhdas