Here are three Hadith that strongly suggest Muhammad didn’t receive His message from a Christian scribe but received it from an Angel Gabriel as He claimed.
Ibn 'Abbas in the explanation of the Statement of Allah. 'Move not your tongue concerning (the Quran) to make haste therewith." (75.16) Said "Allah's Apostle used to bear the revelation with great trouble and used to move his lips (quickly) with the Inspiration." Ibn 'Abbas moved his lips saying, "I am moving my lips in front of you as Allah's Apostle used to move his." Said moved his lips saying: "I am moving my lips, as I saw Ibn 'Abbas moving his." Ibn 'Abbas added, "So Allah revealed 'Move not your tongue concerning (the Qur'an) to make haste therewith. It is for us to collect it and to give you (O Muhammad) the ability to recite it (the Qur'an) (75.16-17) which means that Allah will make him (the Prophet ) remember the portion of the Qur'an which was revealed at that time by heart and recite it. The Statement of Allah: And 'When we have recited it to you (O Muhammad through Gabriel) then you follow its (Qur'an) recital' (75.18) means 'listen to it and be silent.' Then it is for Us (Allah) to make It clear to you' (75.19) means 'Then it is (for Allah) to make you recite it (and its meaning will be clear by itself through your tongue). Afterwards, Allah's Apostle used to listen to Gabriel whenever he came and after his departure he used to recite it as Gabriel had recited it."
Jabir bin Abdullah Al-Ansari:
“While talking about the period of pause in revelation, reported the speech of the Prophet (saw), "While I was walking, all of a sudden I heard a voice from the sky. I looked up and saw the same angel, who had visited me at the cave of Hira, sitting on a chair between the sky and the earth. I got scared of him and came back and said, 'Wrap me (in blankets).' And then Allah (swt) revealed the following Holy Verses (of the Quran): 'O you (Muhammad [saw]) enveloped (in garments)! Arise and warn... (up to) ...and keep away from Ar-Rujz (the idols)!' (V.74:1-5) After this, the revelation started coming strongly and frequently in succession one after the other."
A’isha (the mother of the faithful believers) Al-Harith bin Hisham asked Allah's Apostle "O Allah's Apostle! How is the Divine Inspiration revealed to you?" Allah's Apostle replied, "Sometimes it is (revealed) like the ringing of a bell, this form of Inspiration is the hardest of all and then this state passes ' off after I have grasped what is inspired. Sometimes the Angel comes in the form of a man and talks to me and I grasp whatever he says." 'Aisha added: Verily I saw the Prophet being inspired Divinely on a very cold day and noticed the Sweat dropping from his forehead (as the Inspiration was over).