حَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا عَفَّانُ، حَدَّثَنَا حَمَّادٌ، - يَعْنِي ابْنَ سَلَمَةَ - أَخْبَرَنَا ثَابِتٌ، قَالَ سَمِعْتُ أَنسًا، يَقُولُ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ يَبْقَى مِنَ الْجَنَّةِ مَا شَاءَ اللَّهُ أَنْ يَبْقَى ثُمَّ يُنْشِئُ اللَّهُ تَعَالَى لَهَا خَلْقًا مِمَّا يَشَاءُ ‏"‏ ‏.‏

Anas reported Allah's Apostle (PBUH) as saying: There would be left some space in Paradise as Allah would like that to be left. Then Allah would create another creation as He would like. Translation Not Available

Book Ref: Sahih Muslim Book 53 Hadith 6826
Web Ref:  Sahih Muslim Book 40 Hadith 2848 d