Jaiminīya (Talavakāra) Brāhmaṇa 1.174

1.174

tāṃ pratisamīkṣeta vāmī nāma saṃdṛśi viśvā vāmāni dhīmahi iti
prajā vai vāmam
prajāmeva tadātmandhatte
vṛṣṇaste vṛṣṇyāvato viśvāretāṃsi dhīmahi itītarā pratisamīkṣate
tadāhuḥ prāvṛta udgāyedagnirvā eṣa vaiśvānaro yadyajñāyajñīyaṃ - tasya śāntyā
apradāhāyeti
īśvaro ha tu pitṛdevatyo bhavitoryatprāvṛta udgāyet
atho āhuryāvadeva śrotraṃ tāvatprāvṛtyodgāyediti
tadu vā āhuḥ karṇābhyāṃ vai śṛṇotyakṣibhyāṃ paśyati
tasmādātmānamantariyādyatprāvṛta udgāyet
atho āśiraṃ vai tṛtīye savane'vanayanti
prajā vai paśava āśīḥ
tasmātsarvasmādātmānamantariyādyatprāvṛta udgāyet
aprāvṛta evodgāyediti

He should look back at her, saying: 'Fair one by name in appearance, may we receive all fair things.'
Offspring is indeed the fair thing.
Thus he places offspring in himself.
'From you, the virile, possessing virility, may we receive all seeds,' says the other, looking back.
Regarding this they say: 'Veiled he should chant, for this Yajñāyajñīya is Agni Vaiśvānara—for its appeasement, so that it may not burn.'
However, he is liable to become belonging to the ancestors if he should chant veiled.
And then they say: 'He should chant having veiled only as much as his ear.'
And regarding this they also say: 'With two ears he hears, with two eyes he sees;
therefore he would separate himself [from life] if he should chant veiled.
Moreover, in the third pressing, they pour in the warm milk mixture;
the warm milk mixture is offspring, is cattle;
therefore he would separate himself from all that if he should chant veiled.'
He should chant completely unveiled.