The Prophet ﷺ said, "The mill of Islam will turn for thirty-five, or thirty-six, or thirty-seven years. If they perish, then they will follow the path of those who perished before them. But if their religion endures for them, it will endure for seventy years."I asked, "From what remains, or from what has already passed?"He replied, "From what has already passed."
حدثنا محمد بن سليمان الأنباري حدثنا عبد الرحمن عن سفيان عن منصور عن ربعي بن حراش عن البراء بن ناجية
عن النبي ﷺ قال تدور رحى الإسلام لخمس وثلاثين أو ست وثلاثين أو سبع وثلاثين فإن يهلكوا فسبيل من هلك وإن يقم لهم دينهم يقم لهم سبعين عاما قال قلت أمما بقي أو مما مضى قال مما مضى
Its chain of transmission is hasan.Ahmad narrated it, 1/393, from Abdul-Rahman bin Mahdi with the same chain, and Hakim graded it sahih, 4/521 and 3/114, and Dhahabi agreed with him.Sufyan Thawri stated clearly that he heard it directly, and Shayban bin Abdul-Rahman corroborated him.