The Grihya Sutras, Part 1 (SBE29), by Hermann Oldenberg, , at sacred-texts.com
1 1. The (rites) based on the spreading (of the three sacred fires) have been declared; we shall declare the Grihya (rites).
2 2. There are three (kinds of) Pâkayagñas, the hutas, (i.e. the sacrifices) offered over the fire; over something that is not the fire, the prahutas; and at the feeding of Brâhmanas, those offered in the Brahman.
3 3. And they quote also Rikas, 'He who with a piece of wood or with an oblation, or with knowledge ("veda").'
4 4. Even he who only puts a piece of wood (on the fire) full of belief, should think, 'Here I offer a sacrifice; adoration to that (deity)!'
(The Rik quoted above then says), 'He who with an oblation'and, 'He who with knowledge;' even by learning only satisfaction is produced (in the gods).
Seeing this the Rishi has said, 'To him who does not keep away from himself the cows, to him who longs for cows, who dwells in the sky, speak a wonderful word, sweeter than ghee and honey.' Thereby he means, 'This my word, sweeter than ghee and honey, is satisfaction (to the god); may it be sweeter.'
(And another Rishi says), 'To thee, O Agni, by this Rik we offer an oblation prepared by our heart; may these be oxen, bulls, and cows.' (Thereby he means), 'They are my oxen, bulls, and cows (which I offer to the god), they who study this text, reciting it for themselves (as their Svâdhyâya).'
(And further on the Rik quoted above says), 'He who (worships Agni) with adoration, offering rich sacrifices.' 'Verily also by the performing of adoration (the gods may be worshipped); for the gods are not beyond the performing of adoration; adoration verily is sacrifice'thus runs a Brâhmana.
159:1 1, 1. The spreading (vitâna or, as it is also called, vihâra or vistâra) of the sacred fires is the taking of two of the three sacrificial fires, the Âhavanîya fire and the Dakshinâgni, out of the Gârhapatya fire (see, for instance, Weber's Indische Studien, IX, 216 seq.). The rites based on, or connected with the vitâna; are the rites forming the subject of the Srauta ritual, which are to be performed with the three fires.
159:2 Comp. Sâṅkhâyana-Grihya I, 5, 1; I, 10, 7. The division here is somewhat different from that given by Sâṅkhâyana; what Sâṅkhâyana calls ahuta, is here prahuta ('sacrificed up'); the prahutas of Sâṅkhâyana form here no special category; the prâsitas of Sâṅkhâyana are the brahmani hutâs of Âsvalâyana. Thus Âsvalâyana has three categories, while Sâṅkhâyana (and quite in the same way Pâraskara I, 4, 1) gives four. Nârâyana mentions as an example of prahuta sacrifices the baliharana prescribed below, I, 2, 3.
159:3 Rig-veda VIII, 19, 5, The mortal who with a piece of wood, or with an oblation, or with knowledge worships Agni, who with adoration (worships him) offering rich sacrifices,' &c.
160:4 The words of the Rik, 'with an oblation,' are here repeated, the Vedic instrumental âhutî being replaced and explained by the regular form âhutyâ.
The following Rik is taken from the eighth Mandala, 24, 20. The god compared there with a rutting bull is Indra.
The following verse is Rig-veda VI, 16, 47; we may doubt as to the correctness of the explanation given in our text, by which te te is referred to the persons studying the hymns of the Rishi. All these quotations of course are meant to show that the knowledge of the Veda and the performing of namas (adoration) is equivalent to a real sacrifice.