Sayyid Baqi bin Atwa Hasani has narrated from his father that:
“One day we were sitting together at the time of Isha when Atwashouted. When we went to him, he said: Your Imam Zamana (a.s.) has justleft me. Hurry up so that you might be able to meet him.
We went out and looked here and there but could not see anyone. Wecame back to him and asked him to tell us the whole story.
He said: A few moments ago a person came to me and said: O Atwa! I asked: Who are you?
He replied: I am the Imam of your sons (Atwa was from the Zaidiyyahsect and his sons were Imamite). He said: I have come to get you cured from this malady.
He then touched my navel and pressed it a little and then went away.
Now when I touched and felt it, I saw that I was completely cured. Thenthis incident became very famous. I asked about it from other than the sons of Atwa also and they also verified it.
Reference : Beharul anwar vol 51.52.53 , Part 1 , The Promised Mahdi