´Abu Wa'il narrated from Hudhaifah that 'Umar said:` "Which of you remembers what the Messenger of Allah(s.a.w) said about the Fitnah?" So Hudhaifah said: "I do." Hudhaifah said: "A man's Fitnah is in his family, his wealth, his children, and his neighbors. It is atoned for by the Salat, fasting, charity, and by commanding good and forbidding evil." 'Umar said: "I am not asking you about this. Rather, about the Fitnah that spreads like the waves of the sea." He said: "O Commander of the Believers! Between you and it is a closed door." 'Umar said: "Will it be opened or broken?" He said: "It will be broken." He said: "Then it will never be closed until the Day of Judgement."
Hadith Referenceسنن ترمذي / كتاب الفتن عن رسول الله صلى الله عليه وسلم / 2258