Verse 6.6.2.7

dvābhyām pravṛṇakti | dvipādyajamāno yajamāno'gniryāvānagniryāvatyasya mātrā tāvataivaināmetatpravṛṇakti gāyatryā ca triṣṭubhā ca prāṇo gāyatryātmā triṣṭubetāvānvai paśuryāvānprāṇaścātmā ca tadyāvānpaśustāvataivaināmetatpravṛṇaktyatho agnirvai gāyatrīndrastriṣṭubaindrāgno'gniryāvānagniryāvatyasya mātrā tāvataivaināmetatpravṛṇaktīndrāgnī vai sarve devāḥ sarvadevatyo 'gniryāvānagniryāvatyasya mātrā tāvataivaināmetatpravṛṇakti tayoḥ sapta padāni saptacitiko gniḥ sapta'rtavaḥ saṃvatsaraḥ saṃvatsaro'gniryāvānagniryāvatyasya mātrā tāvattadbhavati

Preview of English translation:

7. With two (verses) he heats it on the fire,—the Sacrificer is two-footed, and the Sacrificer is Agni: as great as Agni is, as great as is his measure, by so much he thus heats it (the pan). [He does so] with a gayatri and a trishtubh verse,—the Gayatri is the vital air, and the Trishtubh the body; and the animal is as much as the vital air and the body: thus by as much as the animal (consists of) he puts that (pan) on the fire. And, again, the Gayatri is Agni, and the Trishtubh is Indra; and the fire relates to Indra and Agni: as great as the fire is, as great as is its measure, by so much he thus heats it. These two (verses) have seven feet (viz. three and four respectively),—the fire-altar consists of seven layers; seven seasons are a year, and Agni is the year: as great as Agni is, as great as is his measure, so great does this become.

For a detailled translation, including proper diacritics and footnotes, go the full English translation.