Ahmed Alhasan is the successor and messenger of Imam Al Mahdi (a.s)
Question 40: What is the reason for Hajj, and what is its purpose?
Answer: In short, Hajj in Islam the attendance at a specific time of the year, in a specific place which is the sacred house of Allah or the Kaaba. So first we must know the attribute of the time and place.
As for the place which is the Kaaba, it is …
By Allah! The Messenger of Allah (sawas) and my fathers the Imams (a.s.) have not left anything from my matter except that they clarified it, for they have described me very accurately, and they clarified my residence. So neither a confusion regarding my matter nor a suspicion regarding my condition remain after this clarification. And my matter is clearer than the sun in the midday. And verily, I am the first of the Mahdis and the Promised Yamani
First Mahdi : Yamani : Ahmed Alhasan 