Language:
كتاب بدء الخلق
59  
Beginning of Creation
(8)
Chapter: The characteristics of Paradise, and the fact that it has already been created
(8)
باب مَا جَاءَ فِي صِفَةِ الْجَنَّةِ وَأَنَّهَا مَخْلُوقَةٌ
Sahih al-Bukhari 3244

Narrated Abu Huraira:

Allah's Messenger (ﷺ) said, "Allah said, "I have prepared for My Pious slaves things which have never been seen by an eye, or heard by an ear, or imagined by a human being." If you wish, you can recite this Verse from the Holy Qur'an:--"No soul knows what is kept hidden for them, of joy as a reward for what they used to do." (32.17)

حَدَّثَنَا الْحُمَيْدِيُّ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا أَبُو الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ قَالَ اللَّهُ أَعْدَدْتُ لِعِبَادِي الصَّالِحِينَ مَا لاَ عَيْنَ رَأَتْ، وَلاَ أُذُنَ سَمِعَتْ، وَلاَ خَطَرَ عَلَى قَلْبِ بَشَرٍ، فَاقْرَءُوا إِنْ شِئْتُمْ ‏{‏فَلاَ تَعْلَمُ نَفْسٌ مَا أُخْفِيَ لَهُمْ مِنْ قُرَّةِ أَعْيُنٍ ‏}‏‏"‏‏.‏
Reference : Sahih al-Bukhari 3244
In-book reference : Book 59, Hadith 55
USC-MSA web (English) reference : Vol. 4, Book 54, Hadith 467
  (deprecated numbering scheme)