They said a man teaches him, a man who barely spoke Arabic.
An accusation that falls apart on its own
Ibn Kathir says the idolators pointed to a non-Arab servant who sold goods by As-Safa. The Prophet ﷺ may have sat and talked with him a little, but the man knew only simple Arabic phrases. How could the Quran, with its eloquent style and perfect meanings, come from him?
When you want to dismiss something, you grab any explanation, even one that makes no sense. A colleague's success? Must be connections. A rushed accusation often says more about us than them.
If I can find any explanation, I don't have to accept it.
An explanation that makes no sense is just a way to avoid the truth.
Before you dismiss something today, ask if your reason would convince a fair person.