The Messenger of Allah ﷺ said, "As-Sa'ud is a mountain of fire which the disbeliever climbs for seventy years, then falls down it for the same length of time, forever."
حدثنا عبد بن حميد حدثنا الحسن بن موسى عن ابن لهيعة عن دراج عن أبي الهيثم
عن رسول الله ﷺ قال الصعود جبل من نار يتصعد فيه الكافر سبعين خريفا ويهوي فيه كذلك أبدا
[Its isnad is daif]. Ahmad narrated it (3/75) from Hasan bin Musa through this route, and it will come again at 3164, 3326. See hadith 2033 regarding the status of Darraj. Amr bin Harith also narrated it from Darraj through this route. Ibn Hibban narrated it in al-Ihsan (7424), and Hakim (2/507, 534, 4/596) narrated it and graded it sahih, and Dhahabi concurred with him (!).