`Umar asked the people, "Who remembers the narration of the Prophet (ﷺ) about the affliction?" Hudhaifa
said, "I heard the Prophet (ﷺ) saying, 'The affliction of a person in his property, family and neighbors is
expiated by his prayers, fasting, and giving in charity." `Umar said, "I do not ask about that, but I ask
about those afflictions which will spread like the waves of the sea." Hudhaifa replied, "There is a
closed gate in front of those afflictions." `Umar asked, "Will that gate be opened or broken?" He
replied, "It will be broken." `Umar said, "Then the gate will not be closed again till the Day of
Resurrection." We said to Masruq, "Would you ask Hudhaifa whether `Umar knew what that gate
symbolized?" He asked him and he replied "He (`Umar) knew it as one knows that there will be night
before tomorrow, morning.
Sahih al-Bukhari Book 30, Hadith 5