Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.1.15

2.5.1.15

athātaḥ payasyaiva | payaso vai prajāḥ sambhavanti payasaḥ sambhūtāstadyata eva sambhūtā yataḥ sambhavanti tadevābhya etatkaroti tadyāḥ pūrvairhavirbhiḥ prajāḥ sṛjate tā etasmātpayasa etasyai payasyāyai sambhavanti

Thereupon follows the oblation of curds (payasyâ). Now it is on milk that the creatures subsist, it was by means of milk that they were preserved: hence he now offers to them that by which they were preserved, and whereon they subsist; and the beings whom he creates by means of the foregoing offerings, subsist on that milk, on that oblation of curds.