As for the fact that the Black Stone, which is special from The Kaa'ba, its what Allah has commanded Muhammad (pbuh & his Family) to face, that is because The Stone indicates towards The Mahdi, and The Mahdi, or Joseph (Yusuf) of The Family of Muhammad is The Qiblah of Muhammad (pbuh & his Family) and The Family of Muhammad (pbut), for all of them have given glad tidings about him (The Mahdi pbuh), and particpated in preparing the way for establishing The State of The Divine Justice which The Mahdi is going to establish.
`O Ahmed `O Abdullah `O Mahdi from you O AhlulBayt is Goodness , and upon you is Goodness , and in you is Goodness.