كتاب الفتن
Afflictions and the End of the World
Chapter: “And fear the Fitnah which affects not in particular those among you who do wrong….”
Sahih al-Bukhari 7050

Narrated Sahl bin Sa`d:

I heard the Prophet (ﷺ) saying, "I am your predecessor at the Lake-Fount (Kauthar), and whoever will come to it, will drink from it, and whoever will drink from it, will never become thirsty after that. There will come to me some people whom I know and they know me, and then a barrier will be set up between me and them."

حَدَّثَنَا يَحْيَى بْنُ بُكَيْرٍ، حَدَّثَنَا يَعْقُوبُ بْنُ عَبْدِ الرَّحْمَنِ، عَنْ أَبِي حَازِمٍ، قَالَ سَمِعْتُ سَهْلَ بْنَ سَعْدٍ، يَقُولُ سَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ ‏ "‏ أَنَا فَرَطُكُمْ، عَلَى الْحَوْضِ، مَنْ وَرَدَهُ شَرِبَ مِنْهُ، وَمَنْ شَرِبَ مِنْهُ لَمْ يَظْمَأْ بَعْدَهُ أَبَدًا، لَيَرِدُ عَلَىَّ أَقْوَامٌ أَعْرِفُهُمْ وَيَعْرِفُونِي، ثُمَّ يُحَالُ بَيْنِي وَبَيْنَهُمْ ‏"‏‏.‏
Reference : Sahih al-Bukhari 7050
In-book reference : Book 92, Hadith 3
USC-MSA web (English) reference : Vol. 9, Book 88, Hadith 174
  (deprecated numbering scheme)