Aitareya Āraṇyaka 1.3.2

1.3.2

tad āhuḥ.
kaitasyāhnaḥ pratipad iti \
manaś ca vāk ceti brūyāt \
sarve 'nyasmin kāmāḥ śritāḥ.
sarvān anyā kāmān duhe \
manasi vai sarve kāmāḥ śritā.
manasā hi sarvān kāmān dhyāyati \
sarve hāsmin kāmāḥ śrayante ya evaṃ veda \
vāg vai sarvān kāmān duhe.
vācā hi sarvān kāmān vadati \
sarvān hāsmai kāmān vāg duhe, ya evaṃ veda \
tad āhur.
naitad ahar ṛcā na yajūṣā na sāmnā pratyakṣāt pratipadyeta.
narco na yajuṣo na sāmna iyād iti \
tad etā eva vyāhṛtīḥ purastā/j japet \
bhūr bhuvaḥ svar ity etā vāva vyāhṛtaya.
ime trayo vedā.
bhūr ity eva ṛgvedo.
bhuva iti yajurvedaḥ.
svar iti sāmavedaḥ \
tan narcā na yajuṣā na sāmnā pratyakṣāt pratipadyate.
narco na yajuṣo na sāmna eti \\ 2 \\

And here they ask: 'What is the beginning of this day?' Let him say: 'Mind and speech.'

All desires dwell in the one (mind), the other yields all desires.

All desires dwell in the mind, for with the mind he conceives all desires.

All desires come to him who knows this.

Speech yields all desires, for with speech he declares all his desires.

Speech yields all desires to him who knows this.

Here they say: 'Let him not begin this day with a Rik, a Yagus, or a Sâman verse (divine speech), for it is said, he should not start with a Rik, a Yagus, or a Sâman.'

Therefore, let him say these Vyâhritis (sacred interjections) first.

These interjections Bhûs, Bhuvas, Svar are the three Vedas, Bhûs the Rig-veda, Bhuvas the Yagur-veda, Svar the Sâma-veda. Therefore (by intercalating these) he does not begin simply with a Rik, Yagus, or Sâman verse, he does not start with a Rik, Yagus, or Sâman verse.