The below article was based on very incomplete information. It rightfully received a Muslim response which however was not giving all the sources either. We will at some time rework this article in the light of this further information. For now, please also read two follow up articles:
Further comments: 
The original article:
Muhammad had scribes write his revelations down for him. One scribe was `Abdullah Ibn Sa'd Ibn Abi Sarh. As Sarh wrote these revelations down, he frequently made suggestions on improving their wording. Muhammad often agreed and allowed the changes to be made. Eventually, Sarh left Islam, knowing it could not be from God if a mere scribe were allowed to change God's word. Later, after the conquest of Mecca, Muhammad ordered Sarh's death.
During Muhammad's 23 years of prophetic ministry, Muhammad claimed to receive revelations from God, given to him by an angel. Muhammad used many men, functioning as scribes, to write down these assumed revelations. Different scribes wrote down different revelations. `Abdullah Sarh was one of Muhammad's scribes. Evidently, Sarh had some literary skills, sometimes suggesting improvements to Muhammad in the wording of the recited Qur'an. Muhammad often agreed with Sarh's improvements, and allowed the changes to be made.
Sarh eventually left Islam because he knew that no mere scribe should be allowed to change something that was proclaimed to be the word of God. The changes were frequent enough that it caused Sarh to realize that something was amiss. Upon leaving Islam, Sarh became a threat to the credibility of the Qur'an. It would no longer be believed to be the word of God if a man had been allowed to edit and change it. Sarh's threat to the credibility of the Qur'an was also a threat to Muhammad's credibility. No real prophet would allow the word of God to be changed.
Sarh left Islam and lived in Mecca. Some time later, Muhammad and his army moved on Mecca and took it without a fight. On that day, Muhammad ordered the murder of 10 people living in Mecca. Muhammad said "God forbid killing in Mecca, except for this one day." Sarh was one of the people Muhammad ordered to be murdered. His crime? He had left Islam, and he constituted a threat to the credibility of the Qur'an and the prophethood of Muhammad. No wonder then that Muhammad wanted him dead.
PRESENTATION OF ISLAMIC SOURCES
#1 SIRAT RASUL ALLAH
Quoting from "The Life of Muhammad", A Guillaume's a translation of Ibn Hisham's "Sirat Rasul Allah", from page 550: [words in brackets [ ] are mine]
The apostle had instructed his commanders when they entered Mecca only to fight those who resisted them except a small number who were to be killed even if they were found beneath the curtains of the Ka`ba. Among them was `Abdullah b. Sa`d, brother of the B. `Amir b. Lu'ayy. The reason he ordered him to be killed was that he had been a Muslim and used to write down revelation; then he apostatized and returned to Qurahysh [Mecca] and fled to `Uthman b. `Affan whose foster brother he was. [`Uthman was one of Muhammad's closest friends, and later became the Caliph of Islam]. The latter hid him until he brought him to the apostle after the situation in Mecca was tranquil, and asked that he might be granted immunity. They allege that the apostle remained silent for a long time till finally he said yes, [granting `Abdullah immunity from the execution order]. When `Uthman had left he [Muhammad] said to his companions who were sitting around him, "I kept silent so that one of you might get up and strike off his head!" One of the Ansar [Muhammad's helpers from Medina] said, then why didn't you give me a sign, O apostle of God?" He [Muhammad] answered that a prophet does not kill by pointing.
NOTE: the Sirat Rasul Allah is the earliest and most authentic biography of Muhammad. It was even written before the Hadith were compiled.
#2 KITAB AL-TABAQAT AL-KABIR
[Note: words in [ ] brackets are mine]. I have also added ( ) brackets to associate numbers with the people in the list.
Muhammad ordered the execution of 10 people when he took Mecca. Here is the list of names found in Ibn Sa`d "Tabaqat", Vol 2, page 168.
The apostle of Allah entered through Adhakhir, [into Mecca], and prohibited fighting. He ordered six men and four women to be killed, they were (1) Ikrimah Ibn Abi Jahl, (2) Habbar Ibn al-Aswad, (3) Abd Allah Ibn Sa`d Ibn Abi Sarh, (4) Miqyas Ibn Sababah al-Laythi, (5) al-Huwayrith Ibn Nuqaydh, (6) Abd Abbah Ibn Hilal Ibn Khatal al-Adrami, (7) Hind Bint Utbah, (8) Sarah, the mawlat (enfranchised girl) of Amr Ibn Hashim, (9) Fartana and (10) Qaribah.
Occasionally, the Sirat, and the Tabaqat use a different name for the same person. #3 in the list given above is such a case. The differences in the name is due to the amount of family lineage given for the man's name, and the english translation.
Ibn Sa`d corroborates Ibn Ishaq and says on page 174:
A person of al-Ansar had taken a vow to kill Ibn Abi Sarh [the already mentioned Abdallah] if he saw him. `Uthman whose foster brother he (Ibn Abi Sarh) was, came and interceded for him with the prophet. The Ansari was waiting for the signal of the prophet to kill him. `Uthman interceded and he [Muhammad] let him go. The the apostle of Allah said to the Ansari, "Why did you not fulfil your vow?" He said, "O apostle of Allah! I had my hand on the hilt of the sword waiting for your signal to kill him." The prophet said signalling would have been a breach of faith. "It does not behave the prophet to make signal."
NOTE ON THE TABAQAT:
The Tabaqat was translated into English by Moinul Haq, a Pakistani. His work was published by the Pakistan Historical Society. It is published in English in two volumes. The title means "Book of the Major Classes". It is basically a biography of Muhammad.
#3 From Al-Sira by al-'Iraqi
The scribes of Muhammad were 42 in number. `Abdallah Ibn Sarh al-`Amiri was one of them, and he was the first Quraishite among those who wrote in Mecca before he turned away from Islam. He started saying, "I used to direct Muhammad wherever I willed. He would dictate to me 'Most High, All-Wise', and I would write down 'All-Wise' only. Then he would say, 'Yes it is all the same'. On a certain occasion he said, 'Write such and such', but I wrote 'Write' only, and he said, 'Write whatever you like.'" So when this scribe exposed Muhammad, he wrote in the Qur'an, "And who does greater evil than he who forges against God a lie, or says, 'To me it has been revealed', when naught has been revealed to him." So on the day Muhammad conquered Mecca, he commanded his scribe to be killed. But the scribe fled to `Uthman Ibn `Affan, because `Uthman was his foster brother (his mother suckled `Uthman). `Uthman, therefore, kept him away from Muhammad. After the people calmed down, `Uthman brought the scribe to Muhammad and sought protection for him. Muhammad kept silent for a long time, after which he said yes. When `Uthman had left, Muhammad said "I only kept silent so that you (the people) should kill him."
The above quotation in both English and Arabic is from the respective edition of Is the Qur'an Infallible? by `Abdallah `Abd al-Fadi, Order Number VB 4009 E, Light of Life, P.O. Box 13, A-9503 Villach, Austria. The book is availabe in English, and the original Arabic edition.
Al-Iraqi refers to Sura 6:93 above. From Dawud's translation Sura 6:93 reads:
Who is more wicked than the man who invents a falsehood about God, or says: "This was revealed to me", when nothing was revealed to him? Or the man who says, "I can reveal the like of what God has revealed"?
#4 Al-Baidawi commenting on the Qur'an, Sura al-An`am 6:93
"'To me it has been revealed', when naught has been revealed to him" refers to `Abdallah Ibn Sa`d Ibn Abi Sarh, who used to write for God's messenger. The verse (23:12) that says, "We created man of an extraction of clay" was revealed, and when Muhammad reached the part that says, "... thereafter We produced him as another creature (23:14), `Abdallah said, "So blessed be God the fairest of creators!" in amazement at the details of man's creation. The prophet said, "Write it down; for thus it has been revealed." `Abdallah doubted and said, "If Muhammad is truthful then I receive the revelation as much as he does, and if he is a liar, what I said is a good as what he said."
Quoted from the famous Tafsir Anwar al-Tanzil wa Asrar al-Ta'wil by `Abdallah Ibn `Umar al-Baidawi.
Above I presented the details and the context behind the order to murder `Abdullah ibn Sarh. He was a threat to the credibility of the Qur'an. He was a Muslim, worked with Muhammad in writing down the Qur'an, and, from time to time he suggested some minor changes, or made deliberate omissions or additions. `Abdullah eventually realized that if this Qur'an were truly from God, no changes would be made at his suggestion. Sarh realized Islam and the Qur'an were false and went back to Mecca.
After Muhammad took Mecca, and issued the order to kill him, he hid out with `Uthman who was one of Muhammad's closest companions. Later Sarh pled for amnesty. Muhammad wanted one of his men to kill him on the spot, but they didn't know if they should, because they couldn't read Muhammad's mind. So, finally, Muhammad gave him amnesty.
We see here that Muhammad really wanted Sarh dead. But Muhammad handled this in a very irrational way. Muhammad issues an edict to have a man executed, but fails to have it carried out because he doesn't want to make a signal with his hand, or wink with his eye??? Why didn't Muhammad kill him himself? If this man had committed such a crime as to cost him his life, why didn't Muhammad see that his death sentence be carried out? What kind of law is that? "You committed a major crime, punishable by death, but I'm going to let you live because I am too proud to signal with my hand."???
Note here that the Qur'an itself, revealed in regard to Sarh in 6:93, calls Sarh extremely wicked.
This shows that Muhammad gave orders willy-nilly. This man committed no major crime, he just exposed Muhammad and the Qur'an. Muhammad just wanted this man killed for personal reasons. People lived or died based on Muhammad's frame of mind, not based on law and justice.
Many Muslims today proclaim that,
"the Qur'an is the speech from Allah, revealed in its precise meaning and wording through the angel Gabriel, transmitted by many, inimitable, unique and protected by Allah Himself against any corruption".
Ahmad von Deffer "Ulum al-Qur'an", p21.
Yet we find that the Qur'an has suffered corruption. Remember, all of the sources I presented are from early, sincere, dedicated, Muslim writers. There were devout Muslims, not moderates or liberals who would change real Islam for their own ease.
So, even in the historical writings of Islam, we find proof of the Qur'an's corruption. Note: These additions by `Abdullah ibn Sarh are still part of the Qur'an today.
1) Why did Muhammad so readily accept Sarh's fragrant addition to his "revelations"?
2) If Muhammad so easily accepted the input of Sarh, could he not have accepted the input of his other scribes and spliced them into the Qur'an?
Modern scholars have shown that the Qur'an's style has been broken, and re-combined together, (see Bell's "Introduction to the Qur'an" for additional details on textual and stylistic flaws within the Qur'an).
3) Since Muhammad liked Sarh's addition, could he not have also added other stories to embellish the Qur'an? Examining the composition of the Qur'an, we find that there are many stories borrowed from other religious sources: the Old Testament, the New Testament, other works of Judaism (the Mishnah, midrashic commentaries like they are found in Rabbi Pirke Eliezer, etc., pre-Islamic religious stories, Sabeanism, other pagan religion, etc.. Could these also have been borrowed?
4) If this story about Sarh were a fabrication, why did so many early Muslim writers document it? Certainly devout Muslims would not document a lie that serves to undermine their faith.
Proof has been presented that the Qur'an has been tainted. Early Muslim writers have showed that there is corruption in the Qur'an. They have also displayed Muhammad's real motives. Sarh did add to the Qur'an; he realized that and left Islam. Muhammad then knew another threat to his credibility existed. After Muhammad took Mecca he ordered Sarh's death to erase the threat. Because of his vanity Muhammad did not have Sarh murdered but had to pardon him. To this day, this corruption in the Qur'an exists. Further, we have seen upon what principles Muhammad really operated on; principles of mood, not of law.
(Copied and slightly adapted from the original at Islam Unveiled with the author's permission.)
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