有效的“伊拉”（ʿIllah）是经文中提及的沙尔阿“伊拉”，即《古兰经》和《圣训》中所提及的那些。因为只有这两者是沙尔阿的经训。因此，基于该“伊拉”而建立的有理由的沙尔阿律例（Hukm Shar‟ai），其“伊拉”是沙尔阿“伊拉”，而非理性“伊拉”。换言之，“伊拉”必须在经文中被明确提及，或隐含提及，或通过推演，或借助类比（Qiyas）而确立。这一“伊拉”与有理由的律例在存在与缺失上相互关联。因此，律例随其“伊拉”而转移。我们发现，某事物在某种情况下因沙尔阿“伊拉”的存在而被禁止，而一旦该“伊拉”消失，这一事物便转为允许。所以，沙尔阿律例随“伊拉”的存在与缺失而转移：“伊拉”存在，律例便存在；“伊拉”不存在，律例也就不存在。

The valid „Illah is the Shar‟ai „Illah that is mentioned in the text from Qur'an and Sunnah, for only these two are the Shar‟ai texts. Therefore, the „Illah upon which the reasoned Hukm Shar‟ai is built is a Shar‟ai „Illah and not a rational „Illah. In other words, „Illah must be mentioned in the text either explicitly or implicitly or by deduction or through Qiyas. This „Illah is connected with the reasoned Hukm in presence and absence. Thus the rules revolve with their „Illal. So we find a thing is prohibited in a situation due to the existence of a Shar‟ai „Illah, and if this „Illah disappears that very thing becomes permissible. So the Hukm Shar‟ai revolves with the „Illah in existence and in absence, thus when it exists the Hukm exists, and if the „Illah does not exist the rule doesn't exist either.