فَقَضٰىهُنَّ سَبْعَ سَمٰوٰتٍ فِيْ يَوْمَيْنِ وَاَوْحٰى فِيْ كُلِّ سَمَاۤءٍ اَمْرَهَا ۗوَزَيَّنَّا السَّمَاۤءَ الدُّنْيَا بِمَصَابِيْحَۖ وَحِفْظًا ۗذٰلِكَ تَقْدِيْرُ الْعَزِيْزِ الْعَلِيْمِ ( فصلت: ١٢ )
Faqadaahunna sab'a samaawaatin fee yawmaini wa awhaa fee kulli samaaa'in amarahaa; wa zaiyannassa maaa'ad dunyaa bimasaabeeha wa hifzaa; zaalika taqdeerul 'Azeezil 'Aleem (Fuṣṣilat 41:12)
And He completed them as seven heavens within two days and inspired [i.e., made known] in each heaven its command. And We adorned the nearest heaven with lamps [i.e., stars, for beauty] and as protection. That is the determination of the Exalted in Might, the Knowing. (Fussilat  : 12)
1 Mufti Taqi Usmani
So He accomplished them as seven skies in two days, and settled in every sky its (due) thing. And We have decorated the closest sky with lamps, and protected it properly. All this is the determination of the All-Mighty, the All-Knowing.