Ghaibat Tusi: It is narrated from Ahmad bin Ali Raazi from Muhammad binAli from Muhammad bin Abde Rabb Ansari Hamadani from Ahmad bin AbdullahHashmi a descendant of Abbas that he said:
“One day in Sarmanra when His Eminence, Imam Hasan Askari (a.s.)passed away I went to his house. When his bier was taken out of his chamberand placed outside, we were thirty-nine persons who come to attend thefuneral. Just then a child who apparently seemed to be ten years old, came out with a sheet on his shoulder and face. As soon as he entered, such an awe struck us that we rose up to welcome him. He stood up and all of us stood behind him. He recited the funeral prayers and then went away. But he did not go back into the room from which he had emerged; he went into another room.”
Abu Abdullah Hamadani says: “I met Ibrahim bin Muhammad Tabrizi in Maragha and he also narrated to me the above report of Ahmad bin AbdullahHashmi verbatim.”
Reference : Beharul anwar vol 51.52.53 , Part 1 , The Promised Mahdi