“We were sitting with ‘Umar
and he said: ‘Which of you has remembered a Hadith from the
Messenger of Allah (ﷺ) concerning Fitnah?’” Hudhaifah said: “I
said: ‘I have.’ He said: ‘You are very bold.’ He said: ‘How?’
He said: ‘I heard him say: “The fitnah of a man with regard to
his family, his children and his neigbors are expiated by his
prayers, fasts, charity and enjoining what is good and forbidding
what is evil.” ‘Umar said: ‘This is not what I meant, rather I
meant that which moves like the waves of the sea.’” Hudhaifah
said: “Don’t worry about it, O Commander of the Believers! For
there is a closed door between you and them.” ‘Umar said: “Will
that door be broken or opened?” I said: “No, it will be broken.”
‘Umar said: “Then it will never be closed.’”
We asked Hudhaifah: “Did ‘Umar know what that door meant?” He said: "Yes, just as he knows that there will be night before morning, because I narrated to him a Hadith in which there are no errors.” We were afraid to ask him who the door was, so we said to Masruq: “Ask him." He said: “‘Umar.”
Sunan Ibn Majah Book 36, Hadith 30