Three things which are particularly mentioned in the Quran as unchangeable or immutable or for which there can be no substitute are: (1) Kalimaat-i-Allah (i.e. Allah’s words, precepts, or laws given in the Quran), (2) Sunnat-i-Allah (i.e. Allah’s laws in the universe or nature or His laws about the rise and fall of people or nations), and (3) Khalq-i-Allah (i.e. Allah’s way of making things whereby He has endowed every creation with a certain nature or constitution).
The idea of unchangeability or immutability has been extended by some Muslims to other texts besides the Word of God in the Quran, including books of hadith (most of which were compiled more than two centuries after the death of the Prophet (s.a.w.), and about which the compilers themselves never guaranteed that these were the actual words uttered by the Prophet (s.a.w.), and the texts, laws and interpretations done by or attributed to different Islamic scholars, caliphs or rulers from time to time. This ascription of immutability to the sources of Islamic Law other than the Quran has so far mostly been a hindrance rather than help in the implementation of Islam as a socio-politico-economic system in recent times because of lack of agreement among Muslims on these sources. Every Muslim sect claims to be following the Quran and Sunnah, yet every one of them appear to have their own version of Sunnah, which is even distinguishable from the style of their beard and headgear.
Undoubtedly, guidance must be sought from the judicial precedents of the Prophet (s.a.w) and other judicial authorities of the past by the authorities of our time. But whether these are as immutable as the word of God in the Quran, is a question of serious consideration for any student of Islamic jurisprudence. It needs to be thought whether the objective of cleaning the teeth is more important or cleaning it specifically with a particular length of a branch of particular tree is more important.
There are various degrees regarding the question of extent of immutability in Islamic Laws, including: (1) nothing is permanent (not even the word of God); everything is changeable, (2) only the word of God is unchangeable; every other law is amendable, (3) both the word of God and the word of the Prophet (s.a.w) are unchangeable; every other law is amendable, (4) word of God, the word of the Prophet (s.a.) and the word of the founder of a particular school of thought or a particular Islamic scholar of the past, all are unchangeable.
Whatever we decide the optimal combination of permanence and change in Islamic Jurisprudence, we should not forget to consider what the Quran declares as unchangeable, i.e. kalamat-i-Allah, Sunnat-i-Allah and Khalq-i-Allah.
There is also another way of looking at the question of immutability of sources of Islamic Laws. The Supreme Islamic Law given in the Quran by the Almighty Allah is called al-hukm. As far as al-hukm is concerned, only Allah has the authority to give al-hukm. He does not take any one (not even the Prophet (s.a.w.)) as a partner in al-hukm. No one is authorized to review, revise, reverse or amend His hukm. Hence, Allah’s hukm is the Supreme Law that is immutable and unchangeable, and there is no Supreme Law or hukm parallel to Allah’s hukm.
In addition to the Supreme Law (al-hukm) given in the Quran by Allah, there is another body of law, legislated in the light of the Supreme Law, called al-amr. As far as al-amr is concerned, Allah commanded the Prophet (s.a.w.) to do consultation with the community of believers regarding al-amr. The community of believers are also enjoined to do consultation among them regarding al-amr. Now the point of consideration is that whether a body of law (al-amr) legislated through mutual consultation of a community of believers of a particular space and time can be as immutable as the Supreme Law (al-hukm) given by the Almighty. In the light of the principle of mutual consultation given above, another point that is also of paramount importance is that the interpretation of any individual scholar, whoever he/she may be, cannot be implemented as such without undergoing the process of mutual consultation among the community of believers, made mandatory by the Quran.
In short, one extreme view is that there is no such thing as permanent values or absolute truths; everything is changeable and relative. Another extreme view is that everything that was decided through mutual consultation or otherwise by the Prophet (s.a.w), the caliphs, the Imams, or doctors of Islamic Law centuries ago, is permanent and cannot be amended or changed. Between these two extremes is a point of view that only the word of God is permanent and every other law is changeable or amendable by consultation among the Muslims, either in the parliament of their representatives or through referendum.
 Al-Quran Surah 10: Verse 64; Surah 6: Verse 34; Surah 18: Verse 27; Surah 6: Verse 115
 Al-Quran Surah 33: Verse 62; Surah 35: Verse 43; Surah 48: Verse 23
 Al-Quran Surah 30: Verse 30
 Al-Quran Surah 13: Verse 37
 Al-Quran Surah 12: Verse 40; Surah 12: Verse 67
 Al-Quran Surah 18: Verse 26
 Al-Quran Surah 13: Verse 41
 Al-Quran Surah 3: Verse 159
 Al-Quran Surah 42: Verse 38
 Al-Quran Surah 42: Verse 38