The Qur'anic exegesis (tafsir) of the Damascene Jamal al-Din al-Qasimi (1866-1914), Mahasin al-ta'wil, remains largely unstudied. This general disregard may be due to the reputation his tafsir holds as being derivative, based primarily on transmitted material from the first three centuries of Islam (Muhtasib, 1982; Rumi, 1997); or his renown as a salafi overly concerned with literalism (Pink, 2010); or as a modernist (Pink, 2015; Commins, 2002). These unhelpful classifications have resulted in an underappreciation of some of the unique exegetical tools and methods employed in Qasimi’s work. I will provide a corrective to this through close textual analysis of one aspect of Qasimi’s Mahasin: his use of al-Hakim al-Jishumi’s (d. 494/1101) tafsir work al-Tahdhib. The very fact that use is being made of Jishumi at all is significant, as this has been previously unrecognized in western scholarship. The belief that Jishumi’s work had no reception in the wider sunni exegetical tradition beyond the borders of Zaydi Yemen (Mourad, 2013; Zarzur, 1971) must now be qualified. Qasimi’s use was limited to a single volume of a larger (approximately) eight volume set, brought to Damascus by a traveler to Yemen ('Abd al-Baqi, 1957). This curious history allowed a brief glimpse of Jishumi’s work outside its Zaydi borders to part of the sunni exegetical world, prior to what is known of the large-scale transmission of manuscripts from Yemen to the libraries of Europe in the late 19th C (Schmidtke, 2018; Mourad, 2013). This includes the Vatican, where other copies of the Tahdhib were later seen by Qasimi’s student Zirikli (A'lam, 2002). Qasimi’s acquisition and usage thus lends nuance to our understanding of the history of manuscript transmission and reception of works across borders. It also complicates our understanding of the influence of printed works on knowledge production in the mid 19th C (Shamsy, 2016). Finally, the use of the work of a mu'tazili and Zaydi to elucidate the Qur’an for a sunni audience, in a non-polemical context, forces us to reassess previous classifications of his work within the trajectory of the discipline of exegesis. Overall, this investigation of Qasimi’s use of Jishumi questions the analytical utility of approaching the discipline of exegesis with firm genre distinctions in mind. It further forces us to reconsider the historical transmission and production of knowledge across preconceived theological and geographical boundaries.