Shatapatha Brahmana 9.5.1.53

9.5.1.53

nāma kṛtvāthainamupatiṣṭhate | sarveṇa vā eṣa etamātmanā cinoti sa yadetāmatrātmanaḥ paridāṃ na vadetātra haivāsyaiṣa ātmānaṃ vṛñcītātha yadetāmatrātmanaḥ paridām vadate tayo hāsyaiṣa ātmānaṃ na vṛṅkte ye agnayaḥ pāñcajanyā asyām pṛthivyāmadhi teṣāmasi tvamuttamaḥ pra no jīvātave suveti ye ke cāgnayaḥ pañcacitikā asyām pṛthivyāmadhi teṣāmasi tvaṃ sattamaḥ pro asmānjīvanāya suvetyetadanuṣṭubhā vāgvā anuṣṭubvāgu sarvāṇi candāṃsi sarvairevāsmā etaccandobhirnihnuta upasthāyāgniṃ samārohya nirmathyodavasānīyayā yajate

Having given a name to him, he reverently approaches him; for this (Sacrificer) builds him with his (own) whole self, and were he not to give utterance now to this surrender of his own self, he (Agni) would now take away his (the Sacrificer's) self; but when he now gives utterance to this surrender of his own self, he (Agni) does not take away his self. [He approaches the fire] with the Anushtubh verse (Vâg. S. XVIII, 67), 'What fires of the five races of men there are upon this earth,--thou art the chiefest of them: quicken us unto life!'--the Anushtubh, doubtless, is speech, and all the metres are speech: he thus makes amends to him (Agni) by all the metres. Having stood by the fire, and lifted it, and churned it out, he offers the completing oblation.