أَوَلَمْ يَتَفَكَّرُوا فِي أَنفُسِهِم مَّا خَلَقَ اللَّهُ السَّمَاوَاتِ وَالْأَرْضَ وَمَا بَيْنَهُمَا إِلَّا بِالْحَقِّ وَأَجَلٍ مُّسَمًّى وَإِنَّ كَثِيرًا مِّنَ النَّاسِ بِلِقَاءِ رَبِّهِمْ لَكَافِرُونَ
the promise of Allah. Allah does not fail in His promise, but most of the people do not know. They only know the outside appearance of the life of the world, and they are heedless of the Hereafter. Do they not reflect on themselves? Allah created the heavens and the earth and whatever lies between them in Truth and for an appointed term. truly many of mankind are disbelievers in the meeting with their Lord. Have they not travelled throughout the land to see what was the end of those before them? They were greater than them in power, and they plowed the earth and built it up more than they have built it up. Their messengers came to them with clear proofs. Allah would have never wronged them, but it was they who wronged themselves. Then most evil was the end of the evildoers for denying and mocking the signs of Allah. Allah begins creation; then He will repeat it; then to Him you will be returned.
— Quran 30:6–11
أَفَلَمْ يَسِيرُوا فِي الْأَرْضِ فَتَكُونَ لَهُمْ قُلُوبٌ يَعْقِلُونَ بِهَا أَوْ آذَانٌ يَسْمَعُونَ بِهَا فَإِنَّهَا لَا تَعْمَى الْأَبْصَارُ وَلَٰكِن تَعْمَى الْقُلُوبُ الَّتِي فِي الصُّدُورِ
Have they not travelled throughout the land so their hearts may reason, and their ears may listen? For surely it is not the eyes that are blind but the hearts.
— Quran 22:46
because the blindness of the eyes along with the heart is not harmful, Allah uses this metaphor in contrast to the opposite. For one who’s eyes are blind can reflect and benefit from the heart. Indeed, it is not the sight that becomes blind but the heart that becomes blind.