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Surah 17. Al-Israa
Ayah 12
12 وَجَعَلْنَا ٱلَّيْلَ وَٱلنَّهَارَ ءَايَتَيْنِ ۖ فَمَحَوْنَآ ءَايَةَ ٱلَّيْلِ وَجَعَلْنَآ ءَايَةَ ٱلنَّهَارِ مُبْصِرَةً لِّتَبْتَغُوا۟ فَضْلًا مِّن رَّبِّكُمْ وَلِتَعْلَمُوا۟ عَدَدَ ٱلسِّنِينَ وَٱلْحِسَابَ ۚ وَكُلَّ شَىْءٍ فَصَّلْنَـٰهُ تَفْصِيلًا
[12] Behold! We have created day and night as two signs: We have deprived the sign of night of light and made the sign of day bright to enable you to seek bounty of your Lord and to reckon months and years. Thus We have made everything manifestly distinct.13
13Allah invites man to study the wisdom that underlies variety in the world and not get confused and long for monotonous uniformity. In fact, the whole system is based on variety, distinctiveness and diversity in things. For the sake of illustration let us take the case of the signs of day and night: "You see these underlying opposite things daily in your life. If you just consider the underlying wisdom, you will find that without this variety there would have been hardly any activity in the world. Likewise great wisdom lies in the creation of the people with different temperaments, thoughts and inclinations. If Allah had made all men righteous by birth or annihilated disbelievers and wicked people and left only believers and submissive people in the world, the purpose of men's creation could not leave been realized. Therefore, . it is wrong to desire that there should only be day and no night. The righteous thing is that these people, who have got the light of guidance, should exert their utmost to remove the darkness of deviation. It is their duty that if they find darkness like that of night, they should pursue it like the sun so that the light of guidance should re-appear."