H 172 - Ali bin Muhammad bin Ziyad Saymoori said: I came to Abu Ahmad Ubaidullah bin Abdullah bin Tahir; there was a letter of Imam Hasan Askari before him and it was written therein:

I prayed to Almighty Allah against this transgressor [Mustaeen] and God’s fury would overtake him after three days. On the third day, Mustaeen was divested of Caliphate and killed.