Abu Huraira (Radi'Allahu anhu) reported
Allah's Apostle (Sall'Allahu alaihi wa sallam) 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 (Sall'Allahu alaihi wa sallam) then recited:
"Now no person knows what delights of the eye
are kept hidden (in reserve) for them -
as a reward for their (good) deeds.".
(Al-Qur'an ~ Surah-32 ~ Ayah-17)
(Sahih Muslim ~ Book #040, Hadith #6780)