Prophet Muhammad (peace and blessings be upon him) said:
The fire of hell was burned for 1000 years till it became red. It was then burned for 1000 years till it became white. It was then burned for 1000 years till it became black. It is now intense black in colour. (At- Tirmidhi)
The fire of hell was burned for 1000 years till it became red. It was then burned for 1000 years till it became white. It was then burned for 1000 years till it became black. It is now intense black in colour. (At- Tirmidhi)