Khums is one of undoubted rules of Islam, which can be deduced from the verse "Know that whatever property you may gain, one fifth belongs to God and the Messenger ..." (Anfal: 41) and because according to some jurisprudential views it is considered as the financial resources of the Islamic government, it is also important in terms of public finance law. In Imamiyyah jurisprudence, khums includes all incomes, but in Sunni jurisprudence, there is no such generality. The majority of Sunni scholars have accepted that the word "ghanimtum" has a wide meaning, but have limited this inclusion with arguments such as consensus (ijma'). However, some Imamiyyah jurists at first have limited this word to war booty and then extended its ruling to other incomes based on Islamic narrations! Such a contradictory approach to the interpretation of this verse raises the question of how the Imamiyyah jurisprudential views on the verse were formed and what caused the lexical error for this group of Imamiyyah jurists. This article examines this hypothesis that the most important reason of this disagreement is mistake between the meaning of the Fa'il form (ghanim) and the Fa'ila form (ghanimat). This research is an interdisciplinary study with jurisprudential, interpretive and syntactic methods.