One: It must not contradict a stronger evidence, i.e. it must not contradict a clear text of the Quran and the Sunnah, the consensus, and the statements of the Companions [going by the argument that the statements of the Companions are evidence in the Shariah]. However, any qiyas that contradicts a stronger evidence is known as faasid alitibaar (not worthy of consideration). For instance if somebody argues that a girl can marry off herself without the consent of her waliyy basing his or her argument on the fact that since Islaam allows that she can conclude her transactions by herself without the intervention of her waliyy, we say this is a qiyas that is faasid alitibaar. This is because there is already a statement of the Messenger of Allaah (sallallahu Alayhi wasallam), which says:"There is no nikah except with the consent of a waliyy" (Abu Dawud, Tirmidhi and Ibn Majah)
Two: The ruling of the asl (original matter) must have a known reason; the reason must not be a purely devotional one which is not known to us, i.e. it must not be a hidden reason so as to enable us do the qiyas judiciously. Otherwise the qiyas would be incorrect. For instance when a lady came to Aisha (RA) asking her: Why is a menstruating woman asked to pay back the missed fasts and not the missed prayers?" Aisha (RA) responded: "Are you one of the people from Haroorah ( i.e. the Khawarij)? (The Khawarij believed that a menstruating woman would pay back the missed fasts and prayers) She said: "No, I am only asking" Aisha (RA) said: "When we menstruated (during the time of the Messenger) we would be asked to pay back the missed fasts and not the missed prayers" (Muslim).
In this case Aisha (RA) did not do qiyas asthe lady had wanted.
Three: The reason for the ruling of the asl must be established by a clear text, i.e. it must be specifically mentioned in the Quran or Sunnah as in previous examples; or by a consensus that this is the reason why a particular ruling has been passed on a particular issue. The reason can also be drawn from a sound deduction as in the case of intoxicants the reason for the prohibition of which is drawn from a sound deduction. The scholars of Usool al-fiqh refer to these sources of establishing the iIIah (reason) asmasalik. al-illah
Four: The illah must also agree with the ruling, i.e. the legislation of the ruling must fulfill the interest why it has been made or ward off the evil that is expected to be prevented.
Five: That the iIIah must certainly be present in the faru(subordinate) just asit is in the Asl.
For instance Allaah said: " ...If one of them or both of them attain old age in your life say not to them a word of disrespect nor shout at them but address them in terms of honour" AI-Israa. (Q I 7[Israi]:23). We can also compare beating them to saying a word of disrespect to them because of a common illah which is the causation of harm on them. Hence the iIIah present in the asl is also present in the faru.
Six: There should be no hindrance which prevents faru from being given the same ruling as the asl.
This article was culled from the publications of Deen Communication Limited