Sunan At-Tirmidhi

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:)