Jaiminīya (Talavakāra) Brāhmaṇa 1.174

1.174

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.