This paper aims to detail the juristic opinion of the great companion Abdullah bin Masoud, may God be pleased with him, with regards to the issue of the inheritance of the grandfather that is divided among full and half brothers and sisters, and to distinguish his opinion from the rest of the well-known opinions that discuss the same matter. The research problem lies in the lack of popularity of hadith on the opinion of Abdullah bin Masoud in the books of jurists.The paper consists of a preface and three chapters. The preface discusses the disagreement amongst the companions regarding the inheritance of the grandfather to the class of brothers. The first chapter covers the agreement between Abdullah bin Masoud's opinion and that of Zaid bin Thabit. The second explains the agreement between Abdullah bin Masoud's opinion and that of Ali bin Abi Talib. The third clarifies what is enacted Arab legislation. The examination of the rules mentioned in this paper is based on induction, description, and analysis methods. The paper concludes with several results and recommendations, such as that the juristic opinion of Abdullah bin Masoud is present in the legal legislation without a reference from the commentators or explanatory notes to that opinion. Also, there is a greater need to reconsider the Egyptian legislation and other legislation that adopted what is in it for reasons explained in due course.