Reason, as one of the fundamental sources of religious epistemology, has long been a point of attention as well as disagreement among theologians. Shaykh al-Mufīd, one of the foremost Imāmī scholars, adopts a rationalist approach in which reason plays a central role in the derivation of legal rulings, and he rejects the unconditional acceptance of transmitted reports. In contrast, Abū Ḥanīfa, relying on analogical reasoning and rational deliberation alongside the textual sources, assigns a distinguished place to reason within his legal system so much so that his school became known as ahlal-ray and is regarded as a prominent expression of juridical rationalism among Islamic legal traditions. Findings of the study indicate that Shaykh al-Mufīd considers reason to be an independent source not only in the domain of doctrine but also in practical rulings, and at times deems it supervisory or even superior to transmission. He employs reason to assess the probative value of scriptural texts, to accept or reject solitary reports, and to analyze theological issues. In contrast, while Abū Ḥanīfa acknowledges the authority of reason in doctrinal matters, he confines its role in legal rulings to the framework of revelation through methodological tools such as qiyās, istiḥsān, and considerations of public interest. Using a descriptive–analytical method and library-based sources, the study concludes that although both scholars employ rational approaches in jurisprudence, Shaykh al-Mufīd positions reason as a supervisor over transmission, whereas Abū Ḥanīfa employs it as an instrument operating within the bounds of transmitted evidence.