The concepts of “property” and “proprietorship” are central in Islamic commercial jurisprudence, particularly in Shaykh al-Ansari’s Makasib al-Muharramah, where they distinguish lawful from unlawful earnings. This study examines Shaykh al-Ansari’s methodological approach to defining property, analyzing his criteria for proprietorship, and comparing them with contemporary juristic and economic perspectives. Shaykh al-Ansari bases proprietorship on the principle of intended lawful benefit (manfa‘ah mahallalah maqsudah), meaning that objects prohibited or restricted by Shari‘ah, regardless of economic value, cannot constitute valid property. Consequently, their trade is impermissible. Modern jurists and economic analysts, however, prioritize rational human behavior and market mechanisms, such as supply and demand, as the basis for proprietorship, allowing emerging assets like cryptocurrencies, financial entitlements, digital goods, and intangible items to be recognized as property. This divergence produces significant implications for contemporary transactions. The study concludes that combining market-based analysis with Shari‘ah principles provides a precise and adaptable framework for modern commercial jurisprudence.