The Prophet ﷺ reported that Allah the Exalted said, "I have prepared for My righteous servants what no eye has seen, no ear has heard, and what has never crossed the heart of any human being." Confirmation of this is found in the Book of Allah : "No soul knows what comfort of the eyes has been hidden for them as a reward for what they used to do" [Sajdah 32:17].
حدثنا ابن أبي عمر حدثنا سفيان عن أبي الزناد عن الأعرج
يبلغ به النبي ﷺ قال قال الله تعالى أعددت لعبادي الصالحين ما لا عين رأت ولا أذن سمعت ولا خطر على قلب بشر وتصديق ذلك في كتاب الله عز وجل {فلا تعلم نفس ما أخفي لهم من قرة أعين جزاء بما كانوا يعملون}
Agreed upon [by Bukhari and Muslim]. Bukhari narrated it in the Book of the Beginning of Creation, Chapter on What Has Been Said Regarding the Description of Paradise and That It Is Already Created, hadith no. 3244, and Muslim, hadith no. 2824, both from the hadith of Sufyan bin Uyayna, with this wording.