Śatapatha Brāhmaṇa ("of a hundred paths") 2.2.1.15

2.2.1.15

sa yadagnaye pavamānāya nirvapati | yadevāsyāsyām pṛthivyāṃ rūpaṃ tadevāsyaitenāpnotyatha yadagnaye pāvakāya nirvapati yadevāsyāntarikṣe rūpaṃ tadevāsyaitenāpnotyatha yadagnaye śucaye nirvapati yadevāsya divi rūpaṃ tadevāsyaitenāpnotyevamu kṛtsnamevāgnimanapanihitamādhatte tasmādu nirvapedevottarāṇi havīṃṣi

Now when he makes offering to Agni Pavamâna, he thereby obtains that form of his (Agni's) which he laid down on this earth; and when he makes offering to Agni Pâvaka, he thereby obtains that form of his which he laid down in the ether; and when he makes offering to Agni Suki, he thereby obtains that form of his which he laid down in the sky: and thus he lays down the entire Agni unmutilated. For this reason also he should take out the oblations subsequent (to the full-offering).