Śatapatha Brāhmaṇa ("of a hundred paths") 2.1.4.13

2.1.4.13

bhūriti vai prajāpatiḥ | ātmānamajanayata bhuva iti prajāṃsvariti paśūnetāvadvā idaṃ sarva yāvadātmā prajā paśavaḥ sarveṇaivādhīyate

With 'bhûh!' Pragâpati generated the Self; with 'bhuvah!' the (human) race; with 'svah!' the animals (pasu). As much as are the Self, the (human) race, and the animals, so much is this universe: with the universe it (the fire) is accordingly established.