Sahih Bukhari
Beginning of Creation
Volume: 004 / Book Number: 054 / Hadith Number: 467
Narrated Abu Huraira:
Allah's Apostle 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 Quran:--"No soul knows what is kept hidden for them, of joy as a reward for what they used to do." (32.17)