One of the most common accusations made against the Messenger of Allah (pbuh) was that he wasn’t really illiterate and was perfectly capable of authoring the Quran himself. They say that since he was able to sign a peace treaty, he was therefore able to read and write. 

Yet Dr Shabir Ally explains that this document was drawn up for him and he even needed to ask where his name was written so that he could amend the signature.

Even the Quran confirms the fact that Prophet Muhammad (pbuh) was unlettered. The Prophet lived in a time when poetry was very popular and the Messenger of Allah was never known for any literary works.