فَقَضَىٰهُنَّ سَبْعَ سَمَٰوَاتٍۢ فِى يَوْمَيْنِ وَأَوْحَىٰ فِى كُلِّ سَمَآءٍ أَمْرَهَا ۚ وَزَيَّنَّا ٱلسَّمَآءَ ٱلدُّنْيَا بِمَصَٰبِيحَ وَحِفْظًۭا ۚ ذَٰلِكَ تَقْدِيرُ ٱلْعَزِيزِ ٱلْعَلِيمِ
So He completed them as seven universes in two days, and He assigned to each universe its laws. And We decorated the lower universe with lamps, and for protection. That is the design of the Almighty, the All-Knowing.
The Holy Quran · Fussilat (Explained in detail) · 41:12