ŚVETĀŚVATARA UPANISHAD · 4.18

यदातमस् तन् न दिवा न रात्रिर् न सन् न चासच् छिव एव केवलः ।
तद् अक्षरं तत् सवितुर् वरेण्यं प्रज्ञा च तस्मात् प्रसृता पुराणी ॥

yadātamas tan na divā na rātrir na san na cāsac chiva eva kevalaḥ ।
tad akṣaraṃ tat savitur vareṇyaṃ prajñā ca tasmāt prasṛtā purāṇī ॥

When the light has risen, there is no day, no night, neither existence nor non-existence; Siva (the blessed) alone is there. That is the eternal, the adorable light of Savitri,--and the ancient wisdom proceeded thence.

F. Max Müller · The Upanishads, Sacred Books of the East 15 (1884)