Tafsir of Ash-Shu`ara' 26:130

And do you get for yourselves Masani` as if you will live therein forever! Mujahid said, "This means fortresses built up strong and high and structures that are built to last.''

لعلكم تخلدون

as if you will live therein forever, means, `so that you may stay there forever, but that is not going to happen, because they will eventually cease to be, just as happened in the case of those who came before you.'

وإذا بطشتم بطشتم جبارين