Knowledge of grammar plays a significant role in understanding and interpreting texts. This article aims to explore the “genitive case” in Masnavi and analyze it from a historical syntax perspective to elucidate Rumi’s style and the distinctive usage of this construction in Masnavi compared to other works. The research method used is descriptive-analytical based on a case study. The corpus of the study comprised the six volumes of Masnavi, and data were collected through library research. In the analysis of the findings, the usage of the genitive case, its marker, and its specific forms in Masnavi sentences were determined. The various relationships between the head and its modifier with specific lexical items and combinations marked and desired by Rumi were clarified. Ultimately, the detachment and attachment of the genitive case and noun phrases were determined. The findings showed that a large part of Masnavi’s appeal and charm is due to the linguistic patterns used by Rumi, which is not the result of the rhythm and tone of Masnavi. Still, it should be searched for in meticulous and “detail-oriented” studies of grammatical construction and its morphological and syntactic patterns.