Surah 76. Al-Insan, Ayah 13

 There will be no day or night, sun or moon, winter or summer in Paradise. It will always be bright and temperate.

Cf. xviii. 31.

The sun and the moon as we know them will be no longer there. It will be a new world on a different plane. But to give us an idea of comfort we recall the excessive heat of the sun especially in tropical climates, and the excessive cold of the moon especially in northern climates, and we negative them both. That is, the temperature will be just that delightful one that is most agreeable to our sensations as we know them now. The moon is not mentioned, but Zamharir (excessive cold) is sometimes used for the moon.