Sahih Muslim
The Book Pertaining to Paradise, Its Description, Its Bounties and Its Intimates (Kitab Al-Jannat wa Sifat Naimiha wa Ahliha)
Book Number: 040 / Hadith Number: 6780
Abu Huraira reported Allah's Apostle (may peace be upon him) as saying that: Allah the Exalted and Glorious, said: I have prepared for My pious servants which no eye has ever seen, and no ear has ever heard, and no human heart has ever perceived but it is testified by the Book of Allah. He then recited:" No soul knows what comfort has been concealed from them, as a reward for what they did". (xxxii. 17)