Al Isra’ Ayah 12

وَجَعَلْنَا ٱلَّيْلَ وَٱلنَّهَارَ ءَايَتَيْنِ‌ۖ فَمَحَوْنَآ ءَايَةَ ٱلَّيْلِ وَجَعَلْنَآ ءَايَةَ ٱلنَّهَارِ مُبْصِرَةً لِّتَبْتَغُواْ فَضْلاً مِّن رَّبِّكُمْ وَلِتَعْلَمُواْ عَدَدَ ٱلسِّنِينَ وَٱلْحِسَابَ‌ۚ وَكُلَّ شَىْءٍ فَصَّلْنَـٰهُ تَفْصِيلاً ١٢ We made the day and night as two signs. So We made the sign of the night devoid of light, and We made the sign of the day ?perfectly? bright, so that you may seek the bounty of your Lord and know the number of years and calculation ?of time?. And We have explained everything in detail.