The intricate relationships among the various sources of Islamic legal reasoning have long constituted some of the most vigorously discussed and contentious subjects. These include the relationships between: The Qurʾān and Sunna; text (naṣṣ) and reason (ʿaql); consensus (ijmaʿ) and the Qurʾān and Sunna; the internal dynamics within the religious texts themselves; the connections between analogical reasoning (qiyās) and textual evidence (al-adilla al-lafẓiyya), and others. Notably, the question of how conjectural Sunna (al-sunna al-ẓanniyya) like solitary narrations (pl. al-akhbār al-āḥād) relate to and potentially qualify (taqyīd) or specify (takhṣīṣ) the Qurʾān has been a pivotal topic extensively debated throughout the history of Islamic legal theory. Carrying profound implications on whether or not such solitary narrations possess the epistemic authority to specify and/or qualify the general indication of the Qurʾān or not. This paper aims to trace the historical evolution of the theory permitting ‘specifying of the Qurʾān through solitary reports’ (takhṣīṣ al-Qurʾān bil-khabr al-wāḥid) , analysing perspectives from both Sunnī and Shīʿī traditions. Among Sunnī scholars, the issue sparked numerous debates and stark scholarly divisions. In contrast, the Imāmī Shīʿī majority endorsed such qualification/specification, albeit with certain significant exceptions from early scholars. I will review the major critiques levelled against this specification theory and the responses from its proponents, as well as examine both the methodological and epistemological grounds underlying its construction within Sunnī and Shīʿī legal theories. Additionally, I will address the crucial issue of delineating the relationship between qualifying or specifying the Qurʾān through solitary reports, and the theory of abrogation (naskh) of the Qurʾān through such narrations, along with the consequent implications. Building upon this analysis, I will evaluate and critique the fundamental premises of the specification theory and uncover the extent to which the specification or qualification of the Qurʾān by solitary narrations is present in the practise of ijtihād. This will be done by examining whether the Qurʾān actually contains any general indications (ʿumūmāt), such that a jurist is able to qualify or specify the general indication of the Qurʾān by a solitary report. This entails analysing the legal (sharʿī) nature of the Qurʾānic texts regarding their amenability to generalisation. Ultimately, conclusions will be drawn regarding the extent to which rejecting the theory of specifying or qualifying the Qurʾān through solitary narrations impacts the overall corpus of Islamic legal theory and the juristic edicts (pl. fatāwa) in contemporary times.