On the fourth creative day, God said: “Let luminaries come to be in the expanse of the heavens to make a division between the day and the night; and they must serve as signs and for seasons and for days and years. ”
فَهُوَ أَمَرَ فِي ٱلْيَوْمِ ٱلْخَلْقِيِّ ٱلرَّابِعِ :‏ « لِتَكُنْ نَيِّرَاتٌ فِي جَلَدِ ٱلسَّمَاءِ لِتَفْصِلَ بَيْنَ ٱلنَّهَارِ وَٱللَّيْلِ .‏