A Brief Historical Look at Who First Spoke with the Innovation that the Speech of Allah is Created
None of the Companions (radiyallāhu ‘anhum) narrated anything in this affair, and this deviation was unknown in their time. They believed in everything that was revealed in the Book of Allah and the Sunnah of the Prophet (salallāhu ‘alaihi wasallam) regarding that which Allah described Himself with and that which the Messenger affirmed for Him from His Speech, His Hearing, His Seeing and other than that.
Shaikh al-Islam Ibn Taimiyyah (d. 728H) stated in Minhāj as-Sunnah (6/336):
And the intent is that the Sahābah, may Allah be pleased with them, never fought each other due to any difference in a fundamental from the fundamentals of Islam. And they did not differ in anything from the principles of Islam, not in the Attributes, not in the Pre-Decree (al-Qadar), not in the affairs of labelling and passing judgement (takfeer, etc) and not in the affairs of rulership. They did not differ in this with quarrelsome speech, let alone fighting each other with the sword – rather they were firmly established as it relates to the Attributes of Allah, that He informed us regarding Himself. They would negate from Him (the Most High) resemblance to the creation.”
Who Were the First to Openly State their Denial of the Speech of Allah?
What is known from the books of ‘Aqeedah  is that the first who to have made apparent his denial of the Speech of Allah, the Mighty and Majestic, was Ja’ad Ibn Dirham (d. 124H) and this was at the end of the era of Banu Umayyah.
When he made open his belief, the rulers of Banu Umayyah called for him, so he fled to Kufah in Iraq. He was arrested and then executed on the day of ‘Eid al-Adhā by Khālid ibn Abdullah al-Qasri, an appointee of Banu Umayyah in Kufah. During the course of his Khutbah to the people, he said:
O people, sacrifice! May Allah accept your sacrifices. Indeed I will kill Ja’ad ibn Dirham as my sacrifice! He claims that Allah did not take Ibrāheem as a friend (khaleel) and that He did not speak to Moosā directly. High is Allah, the Exalted, the Great, above what al-Ja’ad has said” Then al-Qasri descended and slaughtered Ja’ad at the foot of the mimbar. 
However before he was executed, he passed his innovation on to Jahm Ibn Safwan of Tirmidh (d. 128H) whom he met in Kufah. He was banished to Tirmidh and remained there until he was executed in Asbahan or in Marw by Salām ibn Ahwaz.
Then this innovation passed from the followers of Jahm to Bishr al-Mareesee (d. 218H) who was the head of the Jahmiyyah and their scholar in his era. He is Bishr ibn Ghiyaath ibn Abee Kareemah al-Mareesee. He was from the people of opinion (As’hāb Ar-Ra’ee) who busied himself with ‘ilm al-kalām (theological rhetoric) and he claimed, amongst other evil sayings that have been narrated from him that the Qur’an was created. The scholars charged him with unbelief due to these sayings. His followers are a sect known as the Mareesiyyah. 
Then Ahmad Ibn Abee Duwaad (d. 240H) took this creed from Bishr. And it was he who incited the ruler, Al-Ma’moon Al-‘Abbāsee, to set up the mihnah (the inquisition), and to compel the people to say that the Qur’an is created under the threat of punishment, torture, imprisonment and execution. Many people were put to trial and were compelled to agree. However, the Imām of Ahlus-Sunnah, Ahmad ibn Hanbal (rahimahullāh, died 241H), remained steadfast upon the truth and remained resolute even though he was beaten, tortured and imprisoned.
So we know from that which has preceded that the first to propound the belief negating the Speech of Allah in Islam was al-Ja’ad Ibn Dirham (executed 124H). And we can see that he had successors who inherited this doctrine from him and they led astray many people. However, do we have any indication where Ja’ad Ibn Dirham learnt his innovated doctrine?
We have that which has been mentioned by Ibn Asākir and others:
Al-Ja’ad Ibn Dirham took his saying from Bayān ibn Sam’ān, and Bayān ibn Sam’ān  took it from Tāloot the son of the sister of Labeed ibn al-A’sam, and Tāloot took it from his maternal uncle Labeed. And he is the Jew who did magic upon Allah’s Messenger (salallāhu ‘alaihi wasallam), and he used to say that the Tawrāt was created!” 
From this, you can see how corruption entered the Ummah and who are the true founders of those sects that outright deny, distort or explain away the lofty Attributes of Allah. From those attributes is His Speech (Al-Kalām). May Allaah, the Mighty and Majestic, protect us from misguidance every type. All praise is due to Allah, Lord of the Worlds.
 See Sharh Usool I’tiqād Ahlis-Sunnah 2/382, al-Bidāyah wan-Nihāyah 9/35, Fatāwā Ibn Taimiyyah 12/26, al-Wasā’il fee Ma’rifatil-Awā’il 121.
 See al-Bidāyah wan-Nihāyah 9/35, Mizān al-I’tidāl of adh-Dhahabi 1/399.
 See his biography in Tāreekh Baghdād of al-Khateeb al-Baghdādi 7/56, Wafayāt al-A’yān of Ibn Khalakān 1/277, al-Bidāyah wan-Nihāyah of Ibn Katheer 10/281, Mizān al-I’tidāl of Adh-Dhahabi 1/322, and Siyar A’lām an-Nubalā of adh-Dhahabi 10/200.
 Siyar A’lām an-Nubalā of adh-Dhahabi 11/169.
 And he is Bayān ibn Sam’ān an-Nahdi from Bani Tamīm. He appeared in Iraq sometime after 100 AH. He claimed that ‘Ali (radiyallāhu ‘anhu) was divine and that he had within him a divine portion united with his human portion. And then divinity passed after him to Muhammad ibn al-Hanafiyyah (his son) and then to Abu Hāshim the son of Ibn al-Hanafiyyah and then after him to Bayān ibn Sam’ān. Ibn Numair said: “Khālid ibn Abdul-Malik al-Qusree executed him and burnt him in a fire.” See Mizaan al-I’tidaal 1/357.
 al-Bidāyah wan-Nihāyah 9/350, Al-Wasā’il fi Ma’rifatil-Awā’il of as-Suyooti 131-132.