Mundaka 3.04
agnirmūrdhā cakṣuṣī candrasūryau diśaḥ śrotre vāg vivṛtāśca vedāḥ। vāyuḥ prāṇo hṛdayaṃ viśvamasya padbhyāṃ pṛthivī hyeṣa sarvabhūtāntarātmā ॥4॥
Fire is the head; the eyes are the moon and the sun; the directions are the ears; speech manifests as the Vedas. Air is the life-force; the heart is the universe; the earth is by the feet; indeed, this is the inner Ātman of all beings.
Bhāshya 3.04
Lord Vishnu, the inner Ātman, is stationed everywhere in various forms because of his infinite power and playful nature.
"viṣṇvaṅgānāṃ hi nāmāni dyubhvādīni tu sarvaśaḥ। krīḍādiśaktirūpatvāt tajjatvādanyavastuṣu॥"
"Indeed, the names of the limbs of Vishnu, beginning with heaven and earth, are entirely due to the nature of his power and play, he being that is other things."
iti ca ॥4॥
- stated thus as well.