Quran 70:8 from Surah Al-Ma'aarij on Divine Marvels.
يَوۡمَ تَكُونُ ٱلسَّمَآءُ كَٱلۡمُهۡلِ
English translation: (The) Day will be the sky like molten copper
Transliteration: yawma takunu al-samau kal-muh'li