This research addresses the issue of scholars' criticisms of Sibawayh regarding morphological structures used by the Arabs that Sibawayh allegedly overlooked, or so some scholars thought. This issue gained significant traction in the fourth century AH and later, after early Arab scholars had acknowledged Sibawayh as the first to comprehensively list all the morphological structures used by the Arabs. The research focuses on analyzing the underlying reasons for these criticisms, arriving at several key findings, including: the variation in the languages ​​used as sources of evidence; differing scholarly opinions on derivation; the identification of root and augmented letters; the shift of words between nominal, adjectival, and verbal forms; the weakness of some narrations or the singularity of their transmitters; the use of certain words in poetic license; and the possibility that some morphological structures were newly coined or became widespread after Sibawayh's time. Other reasons will be discussed in the research. The morphological correction of Sibawayh should be understood in its scientific and historical context, with a distinction between genuine omissions, methodological differences, and additions arising from the different conditions of argumentation, while emphasizing that Sibawayh’s book will remain the central reference around which the efforts of morphologists revolve in explanation, correction, and interpretation, without any other book replacing it or surpassing it.