A man said to ‘Abdullāh ibn Mas’ūd (raḍī Allāhu ‘anhu), “Tell
us about the Fire, how is it?”
So
Ibn Mas’ūd said to him:
“If you were to see it, your heart would disappear from
its place.”
Source: Sifah an-Nār
(no. 54) of Ibn Abī ad-Dunyā.
Translation source: www.MuSunnah.com