Aitareya Āraṇyaka 1.1.3

1.1.3

gāyatraṃ praugaṃ kuryād ity āhus.
tejo vai brahmavarcasaṃ gāyatrī.
tejasvī brahmavarcasī bhavatīti \
auṣṇihaṃ praugaṃ kuryād ity āhu/r.
āyur vā uṣṇig.
āyuṣmān bhavatīti \
ānuṣṭubhaṃ praugaṃ kuryād ity āhuḥ.
kṣatraṃ vā anuṣṭup.
kṣatrasyāptyā iti \
bārhataṃ praugaṃ kuryād ity āhuḥ.
śrīr vai bṛhatī.
śrīmān bhavatīti \
pāṅktaṃ praugaṃ kuryād ity āhur.
annaṃ vai paṅktir.
annavān bhavatīti \
traiṣṭubhaṃ praugaṃ kuryād ity āhur.
vīryaṃ vai triṣṭu/b.
vīryavān bhavatīti \
jāgataṃ praugaṃ kuryād ity āhur.
jāgatā vai paśavaḥ.
paśumān bhavatīti \
tad u gāyatram eva kuryād.
brahma vai gāyatrī.
brahmaitad a/har.
brahmaṇaiva tad brahma pratipadyate \
tad u mādhuchandasam \
madhu ha sma vā ṛṣibhyo madhuchandāś chandati.
tan madhuchandaso madhuchandastvam \
atho annaṃ vai madhu.
sarvaṃ vai madhu.
sarve vai kāmā madhu.
tad yan mādhuchandasaṃ śaṃsati, sarveṣāṃ kāmānām avaruddhyai \
sarvān kāmān avarundhe, ya evaṃ veda \
tad vaikāhikaṃ rūpasamṛddhaṃ.
bahu vā etasminn ahani kiñca-kiñca vāraṇaṃ kriyate.
śāntyā eva.
śāntir vai pratiṣṭhā-.
-ekāhaḥśāntyām eva tat pra/tiṣṭhāyām antataḥ pratitiṣṭhanti \
pratitiṣṭhati ya evaṃ veda yeṣāṃ caivaṃ vidvān etad dhotā śaṃsati \\ 3 \\

Some say: 'Let him take a Gâyatrî hymn for the Pra-uga. Verily, Gâyatrî is brightness and glory of countenance, and thus the sacrificer becomes bright and glorious.'

Others say: 'Let him take a Ushnih hymn for the Pra-uga. Verily, Ushnih is life, and thus the sacrificer has a long life.'
Others say: 'Let him take an Anushtubh hymn for the Pra-uga. Verily, Anushtubh is valour, and it serves for obtaining valour.'
Others say: 'Let him take a Brihatî hymn for the Pra-uga. Verily, Brihatî is fortune, and thus the sacrificer becomes fortunate.'
Others say: 'Let him take a Paṅkti hymn for the Pra-uga. Verily, Paṅkti is food, and thus the sacrificer becomes rich in food.'
Others say: 'Let him take a Trishtubh hymn for the Pra-uga. Verily, Trishtubh is strength, and thus the sacrificer becomes strong.'
Others say: 'Let him take a Gagatî hymn for the Pra-uga. Verily, cattle is Gagatî-like, and thus the sacrificer becomes rich in cattle.'
But we say: 'Let him take a Gâyatrî hymn only. Verily, Gâyatrî is Brahman, and that day (the mahâvrata) is (for the attainment of) Brahman. Thus he obtains Brahman by means of Brahman.

'And it must be a Gâyatrî hymn by Madhukkhandas,

'For Madhukkhandas is called Madhukkhandas, because he wishes (khandati) for honey (madhu) for the Rishis.

'Now food verily is honey, all is honey, all desires are honey, and thus if he recites the hymn of Madhukkhandas, it serves for the attainment of all desires.

'He who knows this, obtains all desires.'
This (Gâyatrî pra-uga), according to the one-day (ekâha) ceremonial, is perfect in form. On that day (the mahâvrata) much is done now and then which has to be hidden, and has to be atoned for y recitation of hymns). Atonement (sânti) is rest, the one-day sacrifice. Therefore at the end of the year (on the last day but one of the sacrifice that lasts a whole year) the sacrificers rest on this atonement as their rest.

He who knows this rests firm, and they also for whom a Hotri priest who knows this, recites this hymn.