尽管哈乃斐学派等一些学者接受理性推断出的"Illah"（效因），但最有力的观点是，效因必须源自经文。这是因为，除非真主（subhanahu wa ta'ala）已经启示了律例的理由，理智本身无法确定这些理由。效因是将律例扩展到新事物的依据（daleel）。要使这一律例成为有效的沙里亚律令（Hukm Shar'i），即沙里亚的合法裁定，它必须取自立法者的言语（Khitaab），因为沙里亚律令的定义正是立法者关于人的行为的言语。任何不出自立法者言语的律例都会被拒绝，因为它不是启示（Wahiy），而我们只被命令在行为上遵循启示。若在没有经文效因的情况下扩展律例，就如同仅仅因为醋源自酒，便将禁酒的规定延伸到醋上。酒是一种事物，醋是另一种事物。人不能在经文未允许such扩展的情况下，任意扩展律令。如果经文通过某个效因允许了这种扩展，那么这就是有效的沙里亚律令；如果没有，那它只是一种理性判断，在沙里亚中没有价值。

Although some scholars like those from the Hanafi school accept rationale „Illah‟s, the strongest position is that the „Illah must be from the text. This is because the mind is not capable to determining the reasons for the rules unless they have been revealed by Allah (swt). The „Illah is the daleel which allowed the extension of the rule to a new matter. For this rule to be a Hukm Shar‟i i.e. a valid ruling of the Shar‟iah, it must be taken from the speech (Khitaab) of the Legislator since the definition of Hukm Shar‟i is the speech of the Legislator relating to man‟s actions. Any rule which is not from the speech of the legislator is rejected because it is not revelation (Wahiy) and we are ordered only to follow the Wahiy in our actions. To extend the rule without a textual „Illah would be like extending the prohibition of alcohol to vinegar just because vinegar originates from alcohol. Alcohol is one reality and vinegar is another. One cannot arbitrarily extend the Hukm without the text allowing such an extension. If the text allows it through an „Illah, then this is a valid Hukm Shar‟i, if not then it is a rational judgment which has no value in the Shar‟iah.

尽管如此,人无法对其无法感知的事物作出判断。如果造物主没有为我们提供立法的理由(’Illah,即“illah”),那么人又如何能够对其作出判断呢?因此,从Hukm shar‟i(沙里亚律例)的角度来看,理性的“Illah”不仅被否定,而且人本身实际上就不可能对其作出这样的判断。

This is notwithstanding the fact that man is unable to give judgment on that which he cannot sense. If the Creator did not provide us the reason („Illah) for the legislation of the rule then how can man judge it. Thus, not only is the rational „Illah rejected from the viewpoint of Hukm shar‟i but it is practically impossible for man to give such a judgment in the first place.

此外,心智无法在没有法定的沙拉尔义理(Shar‟i „Illah)的情况下进行类比,这一点通过伊斯兰教法规本身的现实情况便能清楚地说明。例如,我们发现相似的事物会被赋予不同的教法裁决(Ahkam),而不同的事物却可能被赋予相同的裁决(Hukm)。心智通常能够在相似的事物之间进行类比,但经文却与这一原则相悖:在没有水的情况下,尘土在所有物质中可以用来进行小净(Wudhu),尽管二者是两种不同的事物。按照伊斯兰教法规定,如果一个女婴在衣服上小便,那么衣服必须清洗;但如果是男婴做同样的事,则只需在上面洒一些水即可。由此可见,相似并不意味着相同的裁决,正如不相似也不意味着不同的裁决。那么,连既有的裁决都无法在没有法定义理的情况下得到合理解释,心智又如何能够为了新的裁决而进行类比呢?

Furthermore, the fact that the mind cannot make analogy without a Shar‟i „Illah is aptly demonstrated by the reality of the Shari‟ah rules themselves. For example, we find similar realities are given different Ahkam while different realities are given the same Hukm. The mind can normally make analogy between similar things but the text contradicts this principle: So in the absence of water, of all things dust are sufficient to make Wudhu even though they are two different things. According to the Shari‟ah rules if a baby girl urinates on clothes then the clothes must be washed but if a baby boy does the same then it is sufficient just to sprinkle some water on it. Thus, similarity does not mean the same Hukm just as dissimilarity does not mean a different Hukm. So how can the mind make analogy for the sake of new Ahkam when even the existing Ahkam cannot be rationalised without a Shar‟i „Illah?