What Al-Baqir عليه السلام Informed Regarding the Occurrence of the Occultation

Narrated to us my father and Muhammad bin Hasan - May Allah be pleased with them - they said: Narrated to us Saad bin Abdullah: Narrated to us Muhammad bin Husain bin Abil Khattab and Muhammad bin Isa from Muhammad bin Abi Umair from Jameel bin Durraj from Muhammad bin Muslim that he said: Abu Ja’far عليه السلام said:
“None responded to the call of the Messenger of Allah صلى الله عليه وعلى آله وسلم before Ali Ibne Abi Talib عليه السلام and Lady Khadija صلى الله عليه وعلى آله وسلم. The Messenger of Allah صلى الله عليه وعلى آله وسلم remained in Mecca for three years (after declaring his mission) as he feared his community and other people.” 
It is a lengthy tradition, a part of which we have presented, as it pertains to the topic of our discussion.