Śatapatha Brāhmaṇa ("of a hundred paths") 3.4.3.6

3.4.3.6

devānāmu ha sma dīkṣitānām | yaḥ samiddhāro vā svādhyāyaṃ vā visṛjate taṃ ha smetarasyaivetaraṃ rūpeṇetarasyetaramasurarakṣasāni jighāṃsanti te ha pāpaṃ vadanta upasameyuriti vai māṃ tvamacikīrṣīriti mājighāṃsīrityagnirhaiva tathā nānyamuvādāgniṃ tathā nānyaḥ

Now, while the gods were consecrated, whichever of them fetched fire-wood or uttered his appointed texts, him the Asura-Rakshas endeavoured to strike--the one by (assuming) the form of this one, and the other by that of another. They came together, upbraiding one another, saying, 'See, what thou hast clone to me! see, how thou hast struck me!' But Agni alone did not speak thus to any one, nor did any one speak thus to Agni.