أَمْ لَهُمْ شُرَكَاءُ شَرَعُوا لَهُمْ مِنَ الدِّينِ مَا لَمْ يَأْذَنْ بِهِ اللَّهُ وَلَوْلَا كَلِمَةُ الْفَصْلِ لَقُضِيَ بَيْنَهُمْ وَإِنَّ الظَّالِمِينَ لَهُمْ عَذَابٌ أَلِيمٌ ﴿۲۱﴾ تَرَى الظَّالِمِينَ مُشْفِقِينَ مِمَّا كَسَبُوا وَهُوَ وَاقِعٌ بِهِمْ وَالَّذِينَ آمَنُوا وَعَمِلُوا الصَّالِحَاتِ فِي رَوْضَاتِ الْجَنَّاتِ لَهُمْ مَا يَشَاءُونَ عِنْدَ رَبِّهِمْ ذَلِكَ هُوَ الْفَضْلُ الْكَبِيرُ ﴿۲۲﴾

﴾21﴿ Am lahum shurakaaa'u shara'oo lahum minad deeni maa lam ya'zan bihil laah; wa law laa kalimatul fasli laqudiya bainahum; wa innaz zaalimeena lahum 'azaabun aleem
﴾22﴿ Taraz zaalimeena mushfiqeena mimmaa kasaboo wa huwa waaqi'um bihim; wallazeena aamanoo wa 'amilus saalihaati fee rawdaatil jannaati lahum maa yashaaa'oona 'inda Rabbihim; zaalika huwal fadlul kabeer

﴾21﴿ Do they have partners (with Allah) who have legislated for them a religion that Allah has not permitted? And if it were not for the decreed term, the matter would have been settled between them. And indeed, the wrongdoers will have a painful punishment
﴾22﴿ You see the wrongdoers fearful of what they have earned, and it will fall upon them. But those who have believed and done righteous deeds will be in the Gardens of Paradise; for them is whatever they desire with their Lord. That is the great bounty

[21] This is a rebuke of shirk in legislation and lawmaking (shirk fī al-tashrī‘ wa al-ḥukm), and it relates to verses 13 and 17 — meaning: in the Divine Law and the Book of Allah the Exalted, shirk and the practices of the polytheists are not permissible.
So has another deity besides Allah made these actions permissible for them? And if so, that deity cannot be considered god — therefore, it becomes clear that shirk in any form is impermissible.
From this verse, many rulings become evident:
1. One form of shirk is shirk in lawmaking and judgment — also called shirk in obedience, shirk in declaring things forbidden (taḥrīm) and shirk in declaring things permissible (taḥlīl).
2. The true legislator (shāri‘) is only Allah the Exalted. If the term is used for a Prophet, it means he is only a conveyor and explainer of Divine Law, not its originator.
3. The imams and mujtahid scholars are not makers of Sharī‘ah — rather, they derive rulings from the Sharī‘ah’s proofs. Thus, sometimes their rulings are correct, and sometimes they may be mistaken.
4. To consider a mujtahid imam, or a commentator, teacher, or spiritual guide, as one who can independently declare things lawful or unlawful — this is also a form of shirk.
5. To follow a scholar or a shaykh in matters of shirk, innovations, or sinful acts is a form of shirk-based imitation (taqlīd shirkī).
6. To follow a mujtahid imam in such a way that when his opinion clearly contradicts a verse of the Qur'an or an authentic and explicit hadith, one still follows that opinion under the excuse that “he knew better than us” — this kind of taqlīd is also misguidance.
[22] In this verse, two groups are mentioned:
1. Those who commit shirk in legislation (shirk fī al-tashrī‘) — to them, a warning of punishment in the Hereafter is given.
2. The monotheists (muwaḥḥidīn) — those who follow authentic legal proofs (dalīl shar‘ī) — for them, glad tidings of reward in the Hereafter are given.