Mundaka 3.04
अग्निर्मूर्धा चक्षुषी चन्द्रसूर्यौ दिशः श्रोत्रे वाग् विवृताश्च वेदाः। वायुः प्राणो हृदयं विश्वमस्य पद्भ्यां पृथिवी ह्येष सर्वभूतान्तरात्मा ॥४॥
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.
"विष्ण्वङ्गानां हि नामानि द्युभ्वादीनि तु सर्वशः। क्रीडादिशक्तिरूपत्वात् तज्जत्वादन्यवस्तुषु॥"
"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."
इति च ॥४॥
- stated thus as well.