Surah 55. Ar-Rahman, Ayah 37

This is one of several legitimate interpretations of the term dihan (see Tabari); another is "freshly tanned [or "red"] leather" synonymous with adim (Zamakhshari); and yet another, "dregs of olive-oil" (Raghib). All these interpretations have one idea in common - namely, the sudden and surprising change (or changes) of colour to which the sky will be subject at the Last Hour.

Melting away like grease or ointment. The red colour will be due to the flames and the heat. The whole of the world as we know it now will dissolve.