Sunan an-Nasai Book 22, Hadith 2237

أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا يَعْقُوبُ، عَنْ أَبِي حَازِمٍ، قَالَ حَدَّثَنِي سَهْلٌ، أَنَّ فِي الْجَنَّةِ، بَابًا يُقَالُ لَهُ الرَّيَّانُ يُقَالُ يَوْمَ الْقِيَامَةِ أَيْنَ الصَّائِمُونَ هَلْ لَكُمْ إِلَى الرَّيَّانِ مَنْ دَخَلَهُ لَمْ يَظْمَأْ أَبَدًا فَإِذَا دَخَلُوا أُغْلِقَ عَلَيْهِمْ فَلَمْ يَدْخُلْ فِيهِ أَحَدٌ غَيْرُهُمْ ‏.‏

Sahi narrated that:in Paradise there is a gate called Ar'Rayyan, it will be said on the Day of Resurrection: "Where are those who used to fast? Would you like to enter through Ar-Rayyan?" whoever enters through it will never thirst again. Then when they have entered it will be closed behind them, and no one but they will enter through it