This article examines the conceptual evolution of the phrase right to the child to the jurisprudential-legal institution of “custody” in Imami jurisprudence and its reflection in Iranian law. The first analysis shows that Truthfulness expresses the priority of a parent in the guardianship of a child, while “custody” under the framework of guardianship is a duty-oriented and expedient institution and its scope is mainly limited to the physical needs of the child. An examination of key narrations introduces the mother’s priority as conditional on factors such as not remarrying or accepting certain conditions and clarifies the role of Truthfulness in determining guardianship. The historical path of evolution shows that before Sheikh Tusi, Righteous was the main criterion for guardianship; after him, “custody” became an independent jurisprudential institution, and in later periods, the practical meaning of Righteous was generalized to guardianship and sponsorship, and the groundwork was laid for the establishment of guardianship. The jurisprudential-legal reflections of this development show the reduction of the nature of the parent-child relationship to the duties of the custodian and the limitation of the scope of guardianship, and have led to ambiguity of the legal nature and conflicting judicial opinions in the Iranian legal system. By providing legislative and judicial recommendations, including clarifying the legal nature of custody and formulating objective criteria for the best interests of the child, the article suggests that returning to the fundamental concept of "right to the child" can provide a more coherent theoretical basis for resolving legislative conflicts and unifying judicial.