Hadith about the death of Abdullah of Hijaz and the reappearance of Imam Mahdi, are they authentic?
Question:
Hadith about the death of Abdullah of Hijaz and the reappearance of Imam Mahdi, are they authentic
There is a hadith from the Prophet (SAW) and Imam Jaffar Al Sadiq (as) stating that Hijaz (Saudi Arabia) will be ruled by a man named Abdullah. Narrations state that when the tyrant dies, Imam Mahdi (ajfs) will appear. It has been over weeks since King Abdullah died, why hasnt our beloved Imam arrived yet?

Answer:
You may face more than one hadith regarding the foregoing issue, some of which are authentic and reliable. But it is difficult to firmly state that the intended Abdullah in hadith was the previous king of Saudi Arabia.
If you go through the narrations, you would see some signs of the reappearance time which are divided into two categories; certain signs and possible signs. Nonetheless according to some narrations reappearance of Imam Mahdi could occur unexpectedly when there is not any of the signs mentioned before. This state is called Bada’[i], Change of destiny.

[i] An open ended and conditional destiny which could be altered or even transformed.