Aitareya Āraṇyaka 1.3.7

1.3.7

tad id āsa bhuvaneṣu jyeṣṭham (RV X 120,1a) iti pratipadyate.
yad vai jyeṣṭhaṃ, tan mahan.
ma/hadvad rūpasamṛddham etasyāhno rūpam \
tāṃ su te kīrtiṃ maghavan ma/hitvā- (RV X 54,1a) -iti.
mahadvad rūpasamṛddham etasyāhno rūpam \
bhūya id vāvṛdhe vīryā/ya- (RV VI 30,1a) -iti.
vīryavad rūpasamṛddham etasyāhno rūpam \
nṛṇām u tvā nṛtamaṃ gīrbhi/r ukthair (RV III 51,4a) ity.
ukthaṃ vā etad ahar.
ukthavad rūpasamṛddham etasyāhno rūpam \
nyūnākṣare prathame pade viharati.
nyūne vai retaḥ sicyate.
nyūne prāṇā , nyūne 'nnādyaṃ pratiṣṭhitam.
eteṣāṃ kāmānām avaruddhyai \
etān kāmān ava/rundhe ya evaṃ veda \
dve daśākṣare bhavata.
ubhayor annādyayor upāptyai, yac ca padvad yac cāpādakam iti \
aṣṭādaśāṣṭādaśākṣarāṇi bhavanti.
yāni daśa nava prāṇā, ātmaiva daśamaḥ.
sātmanaḥ saṃskṛtir.
aṣṭāv-aṣṭā udyante \
aśnute yad-yat kāmayate ya evaṃ veda \\ 7 \\

He begins with the hymn, Tad id âsa, bhuvaneshu gyeshtham (Rv. X, 120). Verily, gyeshtha, the oldest, is mahat, great. Endowed with mahat the form of this day is perfect.

Then follows the hymn, Tâm su te kîrtim maghavan mahitvâ (Rv. X, 54), with the auspicious word mahitvâ.

Then follows the hymn, Bhûya id vavridhe vîryâya (Rv. VI, 30), with the auspicious word vîrya.

Then follows the hymn, Nrinâm u tvâ nritamam gobhir ukthaih (Rv. I, 51, 4), with the auspicious word uktha.

He extends the first two pâdas, which are too small, by one syllable (Rv. X, 120, 1 a, and Rv. VIII, 69, 2 a). Into the small heart the vital spirits are placed, into the small stomach food is placed. It serves for the attainment of these desires. He who knows this, obtains these desires.

The two feet, each consisting of ten syllables (Rv. X, 120, 1 a, b), serve for the gaining of both kinds of food, of what has feet (animal food), and what has no feet (vegetable food).

They come to be of eighteen syllables each. Of those which are ten, nine are the prânas (openings of the body), the tenth is the (vital) self. This is the perfection of the (vital) self; Eight syllables remain in each. He who knows them, obtains whatever he desires.