Narrated Abu Hurairah:
that the Prophet (ﷺ) said: "Allah Most High said: 'I have prepared for My righteous worshipers what no eye has seen, no ear has heard, and no human heart has conceived.'" And that is testified to in Allah's [the Mighty and Sublime] Book: No person knows what is kept hidden for them of delights of the eyes (32:17). (DE)
English reference (DE): Vol. 5, Book 44, Hadith 3197 (DE)
Arabic reference (DE): Book 47, Hadith 3501 (DE)