Adequacy is a highly applied principle in methodology with many effects in positive laws. The principal question of this paper is this: Does full enforcement of a decree by an agent with all its conditions require adequacy and sufficiency of the decree of religious ruler? The findings of this analytical paper indicate that if in case of apparent religious decrees we make a mistake, there will come distress and constriction, which are both religiously rejected. In real decrees, however, adequacy shall be implemented in full. As in emergency cases, despite urgency and pertinent problems, the decrees shall be implemented immediately based on sufficient and adequate decree issued by the religious ruler. In case of death, there is a need for compensation. Any doubt in fulfilment of duty after the emergency, must be removed through resorting to the principle of quittance to issue adequacy. In case of apparent decrees, Imamiyah jurists prescribe lack of adequacy. The late scholar Bojnurdi has mostly resorted to a rational approach and Imam Khomeini – in addition to resorting to reason and narration – attaches importance to the decision of the legislator even to the degree of adequacy of religious duties. This indicates Imam Khomeini’s approach based on common sense in clarifying the fundamentals and principle of Islamic jurisprudence. The approaches – together - by both thinkers suggest that any reason- and narration-based introduction that prescribe sufficiency of duties as the final intention of the legislator, is valid. This approach consolidates expansion of methodologically developed rational viewpoints in safeguarding expediency of the Sharia law.