For more on this topic, see The Straight Path - Finding Guidance in an Age of Confusion
It is not for a believing man or a believing woman, when Allah and His Messenger have decided a matter, that they should [thereafter] have any choice about their affair. And whoever disobeys Allah and His Messenger has certainly strayed into clear error. (Qur’an 33:36)
But no, by your Lord, they will not [truly] believe until they make you, [O Muhammad], judge concerning that over which they dispute among themselves and then find within themselves no discomfort from what you have judged and submit in [full, willing] submission. (Qur’an 4:65)
O you who have believed, obey Allah and obey the Messenger and those in authority among you. And if you disagree over anything, refer it to Allah and the Messenger, if you should believe in Allah and the Last Day. That is the best [way] and best in result. (Qur’an 4:59)
Then We put you, [O Muhammad], on an ordained way concerning the matter [of religion]; so follow it and do not follow the desires of those who do not know. (Qur’an 45:18)
And We have revealed to you, [O Muhammad], the Book in truth, confirming that which preceded it of the Scripture and as a criterion over it. So judge between them by what Allah has revealed and do not follow their desires away from what has come to you of the truth. (Qur’an 5:48)
a. The ʿillah analysis
b. Points of clarification on the above analysis
c. Custom in general rulings and judicial proceedings
d. Putting custom in its correct place
Differences in rulings due to differences in custom are not, in reality, differences in the content of the [divine[ command. That is because the law is laid down on the basis that it is eternal… rather, the difference [in rulings] means that when customs differ, each custom is traced back to a legal principle that rules over that custom.
This is a chapter of great benefit, ignorance of which has caused great error against the Shariah, which has imposed difficulties, hardships, and obligations that cannot be fulfilled, all of which are known to be things that cannot be brought about by the marvelous Shariah which is the highest rank of benefits.
We practice deference to the teachings of the master jurists, and we lack the authority to introduce a new rule on account of the fact that we do not have the capacity to engage in independent legal interpretation[.] Should we then give legal opinions in accordance with what is in the books containing the transmitted views of the master jurists?
the custom of his time, such that if he was present at the time of the newly-emerging custom he would have ruled in a manner contrary to his original ruling. That is why it has been said that among the conditions for [attaining the rank of] ijtihād is knowledge of the customs of people. For many of the rulings differ in accordance with differences in time due to changes in the custom of the people, or the emergence of a necessity, or the corruption of people, such that if the ruling remained in its original form it would have necessarily brought about hardship and harm to the people; and it would have contravened the principles of the Shariah that are based on decreasing hardship, facilitating ease, and removing harm and damage so that the world may run in accordance with the most perfect system and the best of laws. This is why you see many scholars of the madhhab [i.e., the Ḥanafī school of law] have contradicted what has been stated by the mujtahid [i.e., Abū Ḥanīfah] on many points [of law] which he based on what existed during his time—due to their knowledge that if he existed during their time he would have ruled as they did in accordance with the principles of his own madhhab.