Bhagavad Gita 15.6न तद्भासयते सूर्यो न शशाङ्को न पावकः।यद्गत्वा न निवर्तन्ते तद्धाम परमं मम ॥

That supreme abode is selfillumined for Brahman is selfluminous. It existed before the sun, the moon and the fire came into existence during creation. It remains even after they dissolve into the Unmanifested during the dissolution of the world.This verse is taken from the Kathopanishad The sun does not shine there, nor do the moon and the stars, nor does this lightning shine and much less this fire. When It shines, everything shines after It, by Its light, all these shine (Chap.II,5.15). The same idea occurs in the Svetasvatara Upanishad (6.14) and the Mundaka Upanishad (II.2.10). The sun, the moon, etc., derive their light from Para Brahman. Nothing else is needed for illuminating the Supreme Being because It is selfluminous.Dhama paramam Supreme abode or superexcellent seat or Para Brahman.Though the sun is endowed with the power of illumining all, it cannot illumine the Supreme Being.यत् धाम वैष्णवं पदं गत्वा प्राप्य न निवर्तन्ते यत् च सूर्यादिभिः न भासयते तत् धाम पदं परमं मम विष्णोः।That abode, to which having gone, none returns, and which the sun, moon, stars, lightning and fire do not illumine, is the highest abode of Vishnu.(Cf.VIII.21)