Śatapatha Brāhmaṇa ("of a hundred paths") 8.7.3.13

8.7.3.13

atha svayamātṛṇāmupadadhāti | āyoṣṭvā sadane sādayāmītyeṣa vā āyustasyaitatsadanamavata ityeṣa hīdaṃ sarvamavati cāyāyāmityetasya hīdaṃ sarvaṃ cāyāyāṃ samudrasyahyetaddhṛdayaṃ raśmīvatīm bhāsvatīmiti raśmīvatī hi dyaurbhāsvatyā yā dyām bhāsyā pṛthivīmorvantarikṣamityevaṃ hyeṣa imāṃlokānābhāti

He then lays down the Svayamâtrinnâ, with (Vâg. S. XV, 63), 'I seat thee in the seat of the vital power,'--the vital power, doubtless, is yonder (sun), and his seat this is;--'the animating,'--for he (the sun) animates all this universe;--'in the shadow,'--for in his shadow all this universe is;--'in the heart of the sea,'--for this, indeed, is the heart of the (aerial) sea;--'the radiant, the luminous,'--for radiant and luminous is the sky;--'thou that illumines the sky, the earth and the wide air;'--for thus, indeed, does he (the sun) illumine these worlds.