If it had been from other than Allah, they would have found many inconsistencies in it.
Shia known and famous pop-star Abdulhusayn al-Musawi al-Kadhab in his famous shia book “al-Murajiat” listed 100 names of narrators, which were allegedly shias, which were relied upon by Islamic scholars. We have answered to that letter in details. Among many people, Slave of Husayn mentioned imam Yahya ibn Saeed al-Qattan, as if he was shia. (See #95, in that letter).
However other shia author Adil Kamal Abdullah in the book “Dinu an-Nawaseeb” included imam Yahya ibn Saeed al-Qattan among nawaseeb!
So ya rafidah! Was imam al-Qattan faithful shia or nawaseeb?!!!