Allah, the Exalted, says that the Gardens (of Paradise), which the penitent will enter, will be Gardens of ‘Adn, meaning, eternity. These are Gardens that the Most Beneficent promises His servants in the unseen. This means that these Gardens are from the unseen things that they believe in, even though they have never witnessed them. They believe in the unseen out of their strong conviction and the strength of their faith.
Concerning Allah’s statement,

This affirms the fact that this will occur, and that it is a settled matter. Allah does not break His promise, nor does He change it. This is similar to His statement,

His promise is certainly to be accomplished.

This means that His promise will be and there is no avoiding it. Allah’s statement here,

{must come to pass.} This means that it will come to His servants who are striving towards it and they will reach it. There are those commentators who said,

{imnst come to pass.} “This means it is coming, because everything that comes to you, you also come to it. This is as the Arabs say, ‘Fifty years came to me, and I came to fifty years.’ They both mean the same thing (I’m fifty years old).”

Concerning Allah’s statement,

This means that in these gardens of Paradise there is no ignorant, wasteful and useless speech, like there is in this life. He said,

{... but only Salam} This is an indifferent exception, similar Allah’s statement,

No Laghw will they hear therein, nor any sinful speech. But only the saying of: Salam! Salam!

Concerning His statement,

This means, in what is similar to mornings and evenings. This does not mean that there is a night and a day (in Paradise), but they will be living in times that alternate. They will know its lighted times from its lights and illumination. This is as Imam Ahmad recorded from Abu Hurayrah, who said that tlje Messenger of Allah said,

‘’The first group to enter into Paradise will have forms like the form of the moon on a night when it is fill. They ivill not spit, nor will they blow their noses therein. They also will not defecate. Their containers and combs ivill be made of gold and silver and their censers will be of aloeswood. Their sweat will be the fragrance of musk and each of them will have tivo wives. The marrow of their shins will be visible from beneath the skin due to their beauty. They ivill not have any disputes betiveen them, or any hatred. Their hearts will be united like the heart of one man. They will glorify Allah in the morning and evening. «

Firdaws. In it they shall dwell forever.