Shatapatha Brahmana 9.5.1.62

9.5.1.62

sarvāṇi vā eṣa bhūtāni | sarvāndevāngarbho bhavati yo 'gniṃ bhibharti sa yo 'saṃvatsarabhṛtaṃ cinuta etāni ha sa sarvāṇi bhūtāni garbham bhūtaṃ nirhate yo nveva mānuṣaṃ garbhaṃ nirhanti tannveva paricakṣate 'tha kiṃ ya etaṃ devo hyeṣa nāsaṃvatsarabhṛtasya 'rtvijā bhavitavyamiti ha smāha vātsyo nedasya devaretasasya nirhaṇyamānasya medyasānīti

And, indeed, he who carries about Agni becomes pregnant with all beings, and with all the gods; and he who builds him when he has not been carried about for a year kills all beings in the form of an embryo. But, surely, he who kills a human embryo, is despised, how much more then he who kills him (Agni), for he is a god: 'Let no one become an officiating priest for an (Agni) who has not been carried about for a year,' said Vâtsya, 'lest he should be a participator in the killing of this, a god's seed!'