The Shari'ah evidences can be look at in two ways: General broad (إجمالية) and detailed specific (تفصيلية). When we say, "detailed, specific" this simply refers to the specific evidence for a given specific issue. And as for the broad evidences, this refers to the categories of evidence and they are of two types: Those which are agreed upon and those which are not agreed upon.
So those which are agreed upon are the following:
- The Noble Qur'an: It is the speech of Allaah that the Trustworthy Spirit (Jibreel) descended with uppon the heart of Muhammad (sallallaahu alayhi wasallam) in the Arabic language, compiled between the two covers of the mus-haf, beginning with al-Faatihah and ending with al-Naas, which has been narrated to us through large-scale successive transmission (tawaatur).
- The Pure, Authentic Sunnah: Whatever emanates from the Messsenger (sallallaahu alayhi wasallam) of speech, action or approval (of the speech and action of others).
- Consensus (Ijmaa'): The agreement of all of the mujtahideen (jurists, scholars) amongst the Muslims in an era amongst the various eras after the death of the Messenger (sallallaahu alayhi wasallam) upon the legislative ruling upon a matter.
- Analogy (Qiyaas): Putting a situation (occurrence, issue, matter) for which there is no text comprising a ruling alongside a situation for which there is a textual ruling, and applying the same ruling which is in that text because the two situations (or issues) are equivalent in terms of the reason or cause behind the ruling.
As for those which are disagreed upon they are the following:
- Istihsaan: This is when a jurist departs from a clear an apparent (but weak) usage of analogy (qiyaas) to an obscure (but strong) usage of analogy or when he turns away from a universal application of a ruling to an exceptional application of a ruling on account of an evidence he considers to justify this departure.
- al-maslahah al-mursalah: This is a matter of public interest for which the legislation has not legislated any ruling to help attain it and there is not a specific legislative evidence for either its consideration (use) or its elimination (non-use).
- Al-Urf: That upon which the people have become accustomed and traversed upon of speech, or action, or abandonment (of an action) and which has been called habit (aadah).
- al-Istis-haab: This refers to maintaining a ruling built upon a prior situation which has not changed until evidence is established that the prior situation has now changed.
- Previous Legislations: That which the Qur'an or the Sunnah have mentioned of legislative rulings which were legislated for those nations that preceded us upon the tongues of their respective Messengers.
- Madh-hab al-Sahaabee: The saying of a Companion that came from his own opinion and ijtihaad (jurisprudence) and upon which there was no word of agreement from the Companions as a whole.
The Imaams and Scholars of the four well-known madhaahib differed over the usage of these affairs and this led to variation understanding and deduction of evidence in rulings.
Refer to (الملخصات الفقهية الميسرة) "Simple, Summarized Fiqh Principles" (Imaad Ali Jumu'ah, 1434H, Dar al-Nafaa'is).