This study sheds light on the issues in which Sibawayh made a mistake in the book ``Ea'arab of the Qur'an'' for An-Nahas, a grammatical study, where I enumerated these issues and edited them by presenting and discussing the evidence and then concluded them with the opinion of the researchers, with a clear statement of misleading. All this stems from justice and truth, far from fanaticism or inclination toward one scholar without another. The research was divided into an introduction and a preface that included a brief translation of Mark Al-Nahas and a definition of confusion both linguistically and idiomatically, then the issues that Al-Nahas made mistakes in Sibawayh and the issues in which other scholars were mistakenly transferred to Sibawayh. Finally, a conclusion that included the most important results extracted from the research and a list of the most essential approved sources.
Keywords: Al-Nahas, Sibawayh, mistake, mubrad, Basroun, Kufic