(Fuswilath) 41 : 12
فَقَضَاهُنَّ سَبْعَ سَمَاوَاتٍ فِي يَوْمَيْنِ وَأَوْحَىٰ فِي كُلِّ سَمَاءٍ أَمْرَهَا ۚ وَزَيَّنَّا السَّمَاءَ الدُّنْيَا بِمَصَابِيحَ وَحِفْظًا ۚ ذَٰلِكَ تَقْدِيرُ الْعَزِيزِ الْعَلِيمِ
Thus they were formed as seven heavens within two days, and were inspired for each heaven its command, and We decorated worldly heaven with the lamp and made them safe; they are all ordained by the Exalted, All-knowing.
The worldly heaven means the sky visible from the earth. It is decorated with the lamps of the stars. ‘Made them safe’ means it is made like a fort. As mentioned in verses 15: 16-17; 23: 17; 37: 6-8; and 55: 33, without Authority—Adhikr—no human or sprite can pass through that fort. See explanation 36: 38-40; 65: 12; 67: 3-5.