Śatapatha Brāhmaṇa ("of a hundred paths") 1.1.4.8

1.1.4.8

atha havirāvapati | agnestanūrasi vāco visarjanamiti yajño hi tenāgnestanūrvāco visarjanamiti yāṃ vā amūṃ havirgrahīṣyanvācaṃ yacatyatra vai taṃ visṛjate tadyadetāmatra vācaṃ visṛjata eṣa hi yajña ulūkhale pratyaṣṭhādeṣa hi prāsāri tasmādāha vāco visarjanamiti

He then pours the (two portions of) rice (from the winnowing basket into the mortar), with the text (Vâg. S. I, 15 a): 'Thou art the body of Agni, thou the releaser of speech!' For it is (material for) sacrifice, and hence (by being offered in the fire) it becomes Agni's body. 'The releaser of speech,' he adds, because he now releases that speech which he restrained when he was about to take the rice (from the cart). The reason why he now releases his speech, is that the sacrifice has now obtained a firm footing in the mortar, that it has become diffused; and for this reason he says, 'the releaser of speech!'