Aitareyabrahmana 3.25: adhyāya 13, khaṇḍaḥ 1-14

3.25

somo vai rājāmuṣmim̐l loka āsīt, taṃ devāś ca ṛṣayaś cābhyādhyāyan:
katham ayam asmān somo rājāgached iti.
te 'bruvaṃś chandāṃsi: yūyaṃ na imaṃ somaṃ rājānam āharateti. tatheti.
te suparṇā bhūtvodapataṃs.
te yat suparṇā bhūtvodapataṃs,
tad etat Sauparṇam ity ākhyānavida ācakṣate
chandāṃsi vai tat somaṃ rājānam achācaraṃs.
tāni ha tarhi caturakṣarāṇi-caturakṣarāṇy eva chandāṃsy āsan.
sā jagatī caturakṣarā prathamodapatat.
sā patitvārdham adhvano gatvāśrāmyat,
sā parāsya trīṇy akṣarāṇy ekākṣarā bhūtvā
dīkṣāṃ ca tapaś ca harantī punar abhyavāpatat.
tasmāt tasya vittā dīkṣā vittaṃ tapo yasya paśavaḥ santi.
jāgatā hi paśavo, jagatī hi tān āharad
atha triṣṭub udapatat.
sā patitvā bhūyo 'rdhād adhvano gatvāśrāmyat,
= sā parāsyaikam akṣaraṃ tryakṣarā bhūtvā dakṣinā harantī punar abhyavāpatat.
tasmān madhyaṃdine dakṣiṇā nīyante triṣṭubho loke, triṣṭub bhi tā āharat

iii. 25 (xiii. 1). Soma the king was in yonder world, on him the gods and the seers reflected 'How shall Soma the king come to us?' They said to the metres 'Do ye fetch for us this Soma the king.' 'Be it so' (they replied). Having become birds they flew up. In that having become birds they flew up, that (tale) those who know stories call the Sauparṇa; thus

the metres went towards Soma, the king. The metres then were of four syllables each only. The Jagatī being of four syllables first flew up; she having flown up and having gone half of the way felt weary; having laid aside three syllables, and becoming of one syllable, she flew back down again, bearing consecration and fervour. Therefore by him is consecration obtained, is fervour obtained, who has cattle, for cattle are connected with the Jagatī, for the Jagatī brought them back. Then the Triṣṭubh flew up. She having flown up and having gone more than half the way felt weary; she having laid aside one syllable, having become of three syllables, came back again, bearing the sacrificial fees. Therefore at the midday the sacrificial fees are taken, in the place of the Triṣṭubh, for the Triṣṭubh brought them back.