The sun illuminates both internally and externally by expanding its radiation; similarly, the Supreme Personality of Godhead, by expanding His universal form, maintains everything in the creation both internally and externally.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
सोऽमृतस्याभयस्येशो मर्त्यमन्नं यदत्यगात् । महिमैष ततो ब्रह्मन् पुरुषस्य दुरत्ययः
so'mṛtasyābhayasyeśo martyamannaṃ yadatyagāt | mahimaiṣa tato brahman puruṣasya duratyayaḥ
SB 2.6.17