The process of designating an Imam stands as one of the most pivotal and contentious issues in the context of Islamic leadership, serving as a primary locus of discord throughout Islamic history. Not only have diverse methodologies regarding the selection and appointment of an Imam underscored the unique character of Islamic sects, denominations, and doctrinal orientations but they have also engendered intricate debates within the Muslim intellectual tradition. Within this discourse, the Imamiyah School, drawing upon rational, Qur'anic, and Sunnah sources of knowledge, accentuates the significance of appointment and grants a privilege to textual sources (naṣṣ) as the exclusive conduit for discerning and expounding this perspective. Hence, one of the paradigms employed by the Prophet Muḥammad (pbuh) in both the paramount aspect of his mission and in explicating the succession of Imam ʿAlī to his prophetic legacy is characterized by a specific form of designation (tanṣīṣ). Through this approach, the Prophet not only corroborated the appointment but also elucidated and authenticated the essence of this pivotal issue, thereby substantiating his argument for the community. The research findings expound upon a linguistic framework utilized to convey the concept of Imamate, addressing seven titles such as Imamate, caliphate, successorship (wiṣāyah), wilāyat (lit. guardianship), viziership (vizārat), emirate (imārat) and commandership of Amīr al-Muʾminīn, Imam ʿAlī (as), citing examples of these expressions in the Prophetic sayings.