I have a huge book on every Hadith related to the Mahdi, their sources, who narrated them, their explanations, their grading and so on... I'd estimate 95% of Hadith on the Mahdi are pure fabrications by people with wide imagination, al-Suffiyani is a part of these fabrications, sadly some people believe in this idiotic story of the Suffiyani which is Munkar Matnan before it is Munkar Sanadan.