Śatapatha Brāhmaṇa ("of a hundred paths") 13.7.1.1

13.7.1.1

brahma vai svayambhu tapo'tapyata tadaikṣata na vai tapasyānantyamasti hantāham bhūteṣvātmānaṃ juhavāni bhūtāni cāttmanīti tatsarveṣu bhūteṣvātmānaṃ hutvā bhūtāni cātmani sarveṣām bhūtānāṃ śraiṣṭhyaṃ svārājyamādhipatyam paryaittathaivaitadyajamānaḥ sarvamedhe sarvānmedhānhutvā sarvāṇi bhūtāni śraiṣṭhyaṃ svārājyamādhipatyam paryeti

Brahman Svayambhu (the self-existent, n.) was performing austerities. He said this much,-- 'Verily, there is no perpetuity in austerities; well, then, I will offer up mine own self in the creatures, and the creatures in mine own self.' And, accordingly, by offering up his own self in the creatures, and the creatures in his own self, he compassed the supremacy, the sovereignty, and the lordship over all creatures; and in like manner does the Sacrificer, by thus offering all sacrificial essences in the Sarvamedha, compass all beings, and supremacy, sovereignty, and lordship.