The First Meeting of Hesham ibn Hakam with Imam Jafar Sadiq (A.S.)
Hesham's first meeting and contact with the light of Wilayah, Imam Ja'far ibn Muhammad [a], happened after an evolution through different religions and the deep deliberation of the philosophical schools and also the compilation of his book - Refutation of Aristotle. It is quoted that he was first introduced to the Imam [a] by his uncle, Umar ibn Yazid ibn Zebyan. This meeting was arranged by him. Umar ibn Yazid, who was himself a follower of Imam Ja'far al-Sadiq [a] says: "From the beginning Hesham, my brother's son was the follower of Jahm ibn Safvan, one of the leaders of the Mo'atazalah sect and also one of the followers of the Jahamiyah sect. He was a young, witty and impudent person. He had heard about the attributes of the Imam [a]. One day, he requested me to present him to Imam al-Sadiq [a] to have a discussion with him (Imam [a]). As I was aware that Hesham was bold and rude, I said: "I would not do this without his permission."
Then I visited the Imam [a] and asked his permission for Hesham's visit. The Imam said: "Let him come".
After I went a few steps away from the house of the Imam [a] I remembered Hesham's audacity and meanness. I said to myself perhaps Hesham might speak impertinently in the presence of the Imam, so I returned and said (to the Imam): "Hesham is such and such."
The Imam said: "O Umar, perhaps you are afraid of the meeting of Hesham with me."
I became ashamed of myself and understood that I had made a big mistake. Embarrassed I came out of the Imam's house and told Hesham to go to the Imam [a].
When Hesham entered, he asked about his own problems and difficult matters and he received their correct answers.
Then the Imam [a] also asked him a few questions. But as Hesham was amazed and bewildered (due to this being the first meeting with the Imam [a]) he asked for a deadline of a few days. He returned after a few days to the Imam but without any reply to the Imam's questions. He requested him to reply to those questions. The Imam answered all those questions and solved his problems. Again the Imam [a] asked a few more questions which were related to the invalidity of the Jahmiyah sect (until that very day Hesham was a follower of that sect). Hesham again asked for more time.
After a few days later, Hesham again asked me (Umar ibn Yazid) to go to the Imam's [a] residence and obtain permission to see him. When I went to see him (the Imam [a]) and asked for the permission, the Imam [a] told me about a place named "'Herah" and said: "I shall be there tomorrow."
When I went to Hesham and told him about this matter, he became happy.
On the fixed day, Hesham reached there earlier than the Imam [a]. Hesham says: "While I was waiting there, suddenly Imam al-Sadiq [a] appeared in the far distance riding on a donkey, in great show. As he came nearer and nearer, I was impressed more and more by his greatness and splendour. Then he stopped and waited for me to say something. But I was so overwhelmed by his splendour that I could not speak a word. I believed that this formidableness was from God and it was due to the respect and position which the Imam [a] had before God."
Umar ibn Yazid says: "This was the very meeting that changed Hesham. He left his previous sect (religion) and was converted whole-heartedly to the true religion. From that time on he was always in the presence of the 6th Imam [a]." 
The late Mamghani writes: "Hesham asked the Imam [a] about five hundred problems and questions in his first meeting and received correct answers for all of them. As a result he was so much enchanted by the divine greatness of the Imam [a] that as long as he was alive, he was the greatest defender of the Wilayah of the Ahlul Bayt (the guardianship of the Prophet's household [a])."
 This chapter (the first meeting) is quoted from the book - Rejal Kashi.
 The Moatazalah sect is affected by Jahmiyah sect and have accepted all the teachings of Jaham ibn Safwan except the Problem of Jabr (compulsion) Jamaluddin Qasemi Damishqi has mentioned the "Moatazalah" sect as one of the branches of the Jahmiyah sect, in his book (History of al-Jahmiyah and al-Moatazalah), and has attributed most of the latest problems of the speculative theologians of Ash'ari to Jahmiyah.
 Rejal by Kashi.
 Tanghih al-Maghal by Mamghani; "Usul Kafi" vol.2. Pg. 13: all 500 problems and questions belonged to theological complications.