Tafsir of At-Tur 52:17

(Indeed, the righteous will be in gardens and pleasure)

This is the commencement of the mention of the state of the believers, following the mention of the state of the disbelievers, as is the habit of the Glorious Quran in intimidation and encouragement. It is also permissible that it is among the things said to the disbelievers at that time, as an increase in their distress and torment, but the first is more apparent.

The tanween (nunation) in both places is for exaltation—meaning, great gardens and great pleasure. It is also permissible that it denotes categorization—meaning, a type of garden and a type of pleasure specific to them. As for it being a substitute for the possessive (i.e., their gardens and their pleasure), it is not strong, as is not hidden.