Tafseer Ibn Kathir of AL FURQAAN [62]

وَهُوَ الَّذِي جَعَلَ اللَّيْلَ وَالنَّهَارَ خِلْفَةً لِّمَنْ أَرَادَ أَن يَذَّكَّرَ أَوْ أَرَادَ شُكُورًا

And it is He who has made the night and the day in succession for whoever desires to remember or desires gratitude.