Commentary
In verse 89, by saying: وَنَزَّلْنَا عَلَيْكَ الْكِتَابَ تِبْيَانًا لِّكُلِّ شَيْءٍ the Qur'an has been credited as the exposition of everything. It means everything about the religion because the objective of Divine revelation and Prophetic mission concerns with these very things. Therefore, the very effort to cull out answers to problems pertaining to economic sciences from the Qur’ an is an exercise in error. However, the appearance of some implied hint some-where there shall not be deemed contrary to this. Now remains the question that the Qur’ an does not carry answers to all problems of the religion itself, how then, would it be correct to say that it is an exposition of everything'?
The answer is that the Qur’ an, does carry the basic principles concerning all problems, and it is in their light that the Ahadith of the Rasul of Allah clarify these problems. Then, there are some details which are delegated to the principles of Ijma` (consensus) and Al-Qiyas (analogical deduction following the norms set by the Shari` ah of Islam). This tells us that the religious rulings deduced from the Ahadith of the Holy Prophet ﷺ ، and from Ijma` and Qiyas are also, in a way, as stated by the Qur’ an itself.