Śatapatha Brāhmaṇa ("of a hundred paths") 6.4.2.1

6.4.2.1

atha mṛtpiṇḍamabhimṛśati | purīṣyo 'sīti paśavyo 'sītyetadviśvabharā ityeṣa hīdaṃ sarvam bibhartyatharvā tvā prathamo niramanthadagna iti prāṇo vā atharvā prāṇo vā etamagre niramanthattadyo 'sāvagre 'gnirasṛjyata so 'sīti tadāha tamevainametatkaroti

He then touches the lump of clay, with (Vâg. S. XI, 32), 'Thou art the Purîshya,'--that is, 'Thou art favourable to cattle; all-supporting,'--for he (Agni) indeed supports everything here;--'Atharvan was the first that kindled thee, O Agni!'--Atharvan doubtless is the breath, and the breath indeed churned him out (produced him) at first: 'Thou art that Agni who was produced at first,' this he means to say; and that same (Agni) he thus makes it (the lump) to be.