Śatapatha Brāhmaṇa ("of a hundred paths") 6.1.3.3

6.1.3.3

pheno 'bravīt | kvāham bhavānīti tapyasvetyabravītso 'tapyata sa mṛdamasṛjataitadvai phenastapyate yadapsvāveṣṭamānaḥ plavate sa yadopahanyate mṛdeva bhavati

The foam (m.) said, 'What is to become of me?'--'Thou shalt be heated!' he said. It was heated, and produced clay; for indeed the foam is heated, when it floats on the water, covering it; and when one beats upon it, it indeed becomes clay.