Az-Zumar: 73
{حتى} (Until): It is the particle after which sentences are narrated. The narrated sentence following it is conditional, but its apodosis (jazā’) is omitted. It was omitted because it describes the reward of the people of Paradise; its omission indicates that it is something beyond description. Its proper place is after {خالدين} (abiding therein).
It is said: {حتى إذا جاؤوها} (Until, when they reach it), means: they reach it while its gates are opened—that is, "along with the opening of its gates." It is said that the gates of Hell are not opened until its people enter it, whereas the gates of Paradise are opened beforehand, as evidenced by the verse: {جنات عدن مفتحة لهم الابواب} (Gardens of Eden, with gates opened for them) [Sad: 50]. Therefore, the wāw (conjunction) is used, as if to say: "Until they reach it, and its gates have already been opened."
If you ask: How is the term "driving" (sawq) used for both groups?
I say: The "driving" of the people of Hell means forcing them toward it with humiliation and violence, as is done with captives or rebels when they are driven to prison or execution. The "driving" of the people of Paradise refers to the driving of their mounts—for they do not go except while riding—and urging them on to hasten toward the abode of honor and pleasure, just as is done for those who are honored and esteemed when they arrive at the court of a king. How vast is the difference between the two "drivings"!
{طبتم} (You have become pure): From the filth of disobedience and the impurity of sins.
{فادخلوها} (So enter it): This makes entering Paradise a consequence of purity and cleanliness. It is only an abode for the pure and a dwelling for the clean, for it is an abode that God has purified from every filth and made fragrant from every impurity. None shall enter it except those who are compatible with it and described by its qualities. How far our states are from that compatibility, and how weak our efforts are in acquiring that quality—unless the Generous Bestower grants us a sincere repentance that protects our souls from the grime of sins and removes the filth of these hearts.
{خالدين} (Abiding therein): Destined for eternity.
{الارض} (The land): An expression for the place where they reside as they wish, resembling the state of an heir and his freedom to dispose of what he inherits, his vastness within it, and his ability to traverse it in every direction.
If you ask: What is the meaning of {حيث نشاء} (wherever we wish)? Does one of them occupy the place of another?
I say: Each one of them has a garden of indescribable vastness, exceeding all needs, so he occupies whatever part of his garden he wishes and has no need for the garden of another.
{وترى الملائكة حآفين من حول العرش يسبحون بحمد ربهم وقضى بينهم بالحق وقيل الحمد لله رب العالمين}
(And you will see the angels surrounding the Throne, glorifying the praise of their Lord. And it will be judged between them in truth, and it will be said, "Praise to Allah, Lord of the worlds.")