Aitareyabrahmana 3.27

3.27

sā yad dakṣiṇena padā samagṛbhṇāt, tat prātaḥsavanam abhavat.
tad gāyatrī svam āyatanam akuruta,
tasmāt tat samṛddhatamam manyante sarveṣāṃ savanānām.
agriyo mukhyo bhavati,
śreṣṭhatām aśnute ya evaṃ vedātha yat savyena padā samagṛbhṇāt,
tan mādhyaṃdinaṃ savanam abhavat.
tad visraṃsata, tad visrastaṃ nānvāpnot pūrvaṃ savanaṃ.
te devāḥ prājijñāsanta,
tasmiṃs triṣṭubhāṃ chandasām adadhur Indraṃ devatānāṃ,
tena tat samāvadvīryam abhavat pūrveṇa savanenobhābhyāṃ savanābhyāṃ
samāvadvīryābhyāṃ samāvajjāmībhyaṃ rādhnoti ya evaṃ vedātha
yan mukhena samagṛbhṇāt, tat tṛtīyasavanam abhavat
tasya patantī rasam adhayat, tad dhītarasaṃ nānvāpnot pūrve savane.
te devāḥ prājijñāsanta, tat paśuṣv apaśyaṃs.
tad yad āśiram avanayanty, ājyena paśunā caranti,
tena tat samāvadvīryam abhavat pūrvābhyāṃ savanābhyāṃ
sarvaiḥ savanaiḥ samāvadvīryaiḥ samāvajjāmibhī rādhnoti ya evaṃ veda

iii. 27 (xiii. 3). What she grasped with her right foot became the morning pressing; the Gāyatrī made it her own abode; therefore they regard it as the most perfect of all the pressings. The very first he becomes, he attains pre-eminence who knows thus. What she grasped with her left foot became the midday pressing; it slipped; having slipped it did not match the former pressing. The gods sought to remedy this; in it they placed the Triṣṭubh of metres, Indra of deities; thereby it became of equal strength with the former pressing; with the two pressings of equal strength and of similar quality he prospers who knows thus. That which she grasped with her mouth became the third pressing. Flying she sucked its sap; having

its sap sucked, it did not equal the two former pressings. The gods sought to remedy this; they saw it in cattle. In that they pour in an admixture (of milk), and proceed with the (offering of) butter and the animal (offering), thereby it became of equal strength with the previous pressings. With all the pressings of equal strength and of similar quality he prospers who knows thus.