In Deuteronomy 18:20 we read

"But the prophet, which shall presume to speak a word in my name, which I have not commanded him to speak, or that shall speak in the name of other gods, even that prophet shall die."

Muhammad (pbuh) spoke not just a single word, but dictated a whole book in God's name. For twenty three years he spoke exclusively in the name of God Almighty. He was given one hundred and fourteen chapters, all of which were, and are to this day, recited day after day in God's name. Chapters in the Qur'an begin with the words "In the name of God, the Gracious, the Merciful." Yet he did not die, but lived to fulfill his message completely. He himself even narrated in the name of God a similar verse in the Qur'an:

"And if he (Muhammad) had invented false sayings in Our (God's) name, We would have taken him by the right, then We would have severed from him his aorta, and there is none among you who could have held Us off from him"

The noble Qur'an, al-Haaqah(69):46
 

(Remember that the plural form of this verse is the Arabic plural of respect, not the Christian plural of "Trinity," as seen in chapter 14). If the claims of some are true: That Muhammad (pbuh) was an impostor, then did God go to sleep for twenty three years? Of course not! He knew full well what Muhammad (pbuh) was claiming. If he was not telling the truth, why did God not kill him? Why did he allow him to perpetrate a lie that would span fourteen centuries, and eventually come to cover the globe?