Al-Furqan - 25:62

وَهُوَ الَّذِي جَعَلَ اللَّيْلَ وَالنَّهَارَ خِلْفَةً لِّمَنْ أَرَادَ أَن يَذَّكَّرَ أَوْ أَرَادَ شُكُورًا
[25:62]
And He it is Who made the night and the day to follow each other for him who desires to be mindful or desires to be thankful.
And it is He Who made the Night and the Day to follow each other: for such as have the will to celebrate His praises or to show their gratitude.
And He it is Who hath appointed night and day in succession, for him who desireth to remember, or desireth thankfulness.