Where water and earth, fire and air have no footing – there no star does shine nor does the sun shed its light; there the moon glows not, yet no darkness is found. And when a sage, a brahmin, finds understanding through their own sagacity, then, from forms and formless, from pleasure and pain they are released.

Udana 1.10

The sun does not shine there, nor the moon and the stars, nor these lightnings-not to speak of this fire. He shining, everything shines after Him. By His light all this is lighted

Katha Upanishad 2.2.15, Shvetashvara Upanishad VI. 14