كُلُّ شَيْءٍ هَالِكٌ إِلَّا وَجْهَهُ
Everything is perishing except His Face. (Al-Qaṣaṣ 28:88)
Actual perishing means that something in fact ceases to exist. Perishability by possibility means that a created thing has no self-sufficient permanence; its continued existence depends on Allah’s will and power.
The enduring existence of Paradise and Hell is understood using this distinction. Created things are not given eternal, intrinsic self-sufficiency; rather, Allah preserves what He wills.