‌Context & Objective: The Deed of Gift (Aqd-e Hiba) is addressed in only a limited number of provisions within the Iranian Civil Code, which leaves significant interpretative space for the role of ʿUrf (custom) in regulating its application. This legal gap presents challenges in various aspects of gift transactions, such as determining the conditions for possession, revocation, valuation, and ownership stability. The article outlines a discussion on how ʿUrf fills these legislative voids and governs critical aspects of gift contracts under Islamic jurisprudence and Iranian law. The primary objective of the research is to explore how custom functions as a legal mechanism in the absence of detailed statutory guidance, and to answer the central question: To what extent does ʿUrf influence the interpretation and enforcement of Hiba under Iranian and Islamic legal frameworks.
 ‌Method & Approach: This study adopts a doctrinal legal research method, relying on the analysis of statutory texts, jurisprudential doctrines, and judicial practices in Iran. The approach involves systematically categorizing cases where ʿUrf is invoked to interpret or supplement the legal provisions related to Hiba.
 ‌Findings: The research finds that ʿUrf plays a pivotal role in numerous aspects of the Deed of Gift, including determining whether possession has legally occurred (constructive or implied), evaluating whether gifts are conditional or revocable, distinguishing between compensated and uncompensated gifts, assessing the materiality of mistakes, and handling cases where the gifted object is altered or destroyed. It also reveals that judicial reliance on custom varies and often leads to inconsistent outcomes due to the diversity of customs and lack of statutory specificity.
 ‌Conclusion: The article concludes that although ʿUrf provides necessary flexibility in interpreting and applying Hiba-related provisions, its inconsistent application may lead to legal uncertainty and dispute. Therefore, the study recommends that the Iranian legislature enact clearer regulations in areas prone to ambiguity, such as defining constructive possession, establishing criteria for identifying the nature and value of consideration, and addressing liability for latent defects in dangerous gifts or the gifting of claims. These reforms would enhance legal clarity and uniformity in the application of the law governing Deeds of Gift.