What is the Sahifa al-Fatima (S.A.)?

It is narrated from Hammad bin Othman that the Imam Ja’far As-Sadiq (as) has said that the Zanadiqah (Hypocrite Fire-Worshippers) will appear in one hundred and twenty eight. I have myself read about it in the Sahifa al-Fatima.” I asked, “What is the Sahifa al-Fatima?”
The Imam (as) said, “When the Prophet (S) departed from this world, Lady Fatima (as) became very sad and disconsolate. She used to grieve most of the time. To console her, Allah deputed an angel to narrate to her the events to take place in the future. As the angel continued the narration, Amir’ul-Mu’mineen ‘Ali (as) took notes. This compilation is called the Sahifa al-Fatima. This Book does not contain any instructions about Halal and Haram but contains the description of events in store for the future.
Abi Yahya was told by Imam Ja’far As-Sadiq (as), “O AbuYahya! Allah has rewarded us with high status! Every Friday night Allah permits all the Prophets of the past and your current Imam to visit the Firmament When they are in the Firmament, they offer two Rakat each of prayer at every station there. They acquire lot of knowledge during the visit. Your Imam too comes back with a fund of newly acquired knowledge.”