Surah 74. Al-Muddaththir, Ayah 35

"This is but one," etc. There are numerous Signs of Allah, of which Judgment is one, and one of the mightiest portents. Or the reference may be to the waning of the Moon, the decline of the night, and the glorious sunrise, as tokens or symbols of the world renewed when the present transitory world passes away. According to some commentators "This" here refers to Hell.