This research paper focused on the concept of usury and its impact on daily transactions. The study traced the concept of usury in the Quran verses, Sunnah, and Scholars' opinions using the empirical methodology to deal with the problems of this research, such as the definition of usury, the rationale of prohibition, the impact of usury and the acceptable rate of interest, if any. The research paper reached genuine results, which represent a comprehensive usury theory in Sharia. Some of those results are the definition, the rationale of prohibition, the type of usury, the new interpretation for some authorities in both the Quran and Sunnah, the limit of profit in the sale of goods contract and it discloses the economic theory in Sharia which justifies all the research outcomes. The new theory can be applied among not only Islamic communities, but also can be adopted by all human societies notwithstanding their religion as long as they are keen to achieve peace, stability of dealing and the well-being of humanity.