Legal Verses and Fiqh Derivation

Although ar-Razi is primarily celebrated as a theologian rather than a jurist, Mafatih al-Ghayb contains substantial and sophisticated engagement with ayat al-ahkam — the legal verses of the Quran. Ar-Razi belonged to the Shafi'i school of jurisprudence, and this affiliation is evident throughout his treatment of legal passages.

His approach to legal verses integrates usul al-fiqh methodology with linguistic analysis and kalam-influenced reasoning. When treating a verse with legal implications, ar-Razi typically begins by identifying the grammatical and rhetorical features of the text, then surveys the positions of the four major legal schools, then proceeds to evaluate the evidential weight of each position using principles of Shafi'i legal theory. This tripartite structure gives his legal commentary both depth and comparative breadth.

On the verses concerning ritual purity (tahara), ar-Razi engages extensively with the question of what constitutes the ritual washing of the face and hands, the validity of wiping over footwear (khuff), and the conditions for dry ablution (tayammum). His discussions frequently note where the Shafi'i position differs from the Hanafi or Maliki positions and why he considers the Shafi'i reasoning more sound based on the apparent sense (zahir) of the Quranic text and the supporting hadith evidence.

For the verses on inheritance in Surah an-Nisa, ar-Razi's commentary is particularly detailed. He works through the shares allotted to each category of heir with mathematical precision, a reflection of his broader interest in mathematics and systematic reasoning. He also addresses potential conflicts between Quranic inheritance rules and the hadith literature on blocking of inheritance (hajb), showing how the Shafi'i school harmonizes these sources.

Ar-Razi's treatment of the verse on the direction of prayer (qiblah) in al-Baqarah prompted a famous methodological discussion about abrogation (naskh) in the Quran — specifically whether an earlier verse permitting prayer in any direction was abrogated by the Madinan verse commanding prayer toward Makkah. His analysis of the conditions and proofs required to establish abrogation remains a valuable reference in usul al-fiqh discussions.