Sufyan ath-Thawree (rahimahullah) said: If certainty (about the life of hereafter) entered the heart as it should, then the hearts would fly (out of our chests), longing for al-Jannah and fearing the Hellfire! [Sufyan ath-Thawri (rahimahullah), Ibn Hajar al-Asqalani (rahimahullah), Fathul Bari, 1/14]