Śatapatha Brāhmaṇa ("of a hundred paths") 10.2.2.3

10.2.2.3

yatra pūrve sādhyāḥ santi devā iti prāṇā vai sādhyā devāsta etamagra evamasādhayannetadeva bubhūṣantasta u evāpyetarhi sādhayanti paścedamanyadabhavadyajatramamartyasya bhuvanasya bhūneti paścāhaivedamanyadyajñiyamāsa yatkiṃ cāmṛtam

'Where first the perfect gods were,'--the perfect gods, doubtless, are the vital airs, for it is they that perfected him in the beginning when they were desirous of becoming that (body of Pragâpati); and even now, indeed, they do perfect (him).--[Rig-veda X, 149, 3]--'Thereafter this other became meet for sacrifice by the abundance of the immortal world,'--for thereafter, indeed, other things here--whatsoever is immortal--became fit for sacrifice.