Musnad Abu Ya'la al-Mawsili 42:410

On the authority of Abu Sa'id, from the Messenger of Allah (may Allah bless him and grant him peace), he said: "Wail is a valley in Hell; the disbeliever falls in it for forty autumns before he reaches its bottom." And he said: "Al-Sa'ud is a mountain of fire; he ascends it for seventy autumns, then he falls down it likewise, therein forever."