Imamiyyah jurisprudence based on the teachings of the Ahl al-Bayt (peace be upon them). It relies on their teachings in sources and deduction methods. Verse 7 of Surah Al-Imran and the Ridhawi hadith "Whoever refers ambiguous verses of the Quran to its definitive verses" have great capabilities. By focusing on fundamental propositions, they can establish connection among rulings, reduce deduction errors, increase robustness, and systematize jurisprudence. This article, with a descriptive-analytical approach, examines the role and impact of this verse and narration in jurisprudential deduction. In initial stages, features of definitive verses, their effects, and criteria for distinguishing between definitive and ambiguous verses are explained; then, the authority of referring ambiguous verses of the Quran and narrations to definitive verses is discussed. Based on research, definitive jurisprudential verses are: "Self-evident texts with fundamental content, centrality, and authority over other rulings." Finally, the Quran, Sunnah, and , intellectuals' stipulation emphasize referring ambiguous verses to definitive ones.