An essential condition in the orthodox definition of riba is stipulated excess in a loan or debt. This essential condition is traced to al-Jassas. Understanding this issue of stipulated excess is critical to understanding riba. In this paper the stipulated excess in connection with al-Jassas as well as its implication for defining riba and prohibition of interest is examined. A critical examination of the subject shows that pre-Jassas discourse about riba did not include stipulated excess as an essential condition and al-Jassas' changing of the conditions in defining riba is not corroborated by the textual evidences he used.