And He—exalted be He—denounced the notion that servants should take anyone besides Him as a law-giver, saying: “Do they have associate-gods who have laid down for them aspects of the religion for which Allah has given no permission?” (42:21).

Whoever accepts a body of legislation other than Allah’s has committed shirk with Allah. Any act of worship that Allah and His Messenger have not prescribed is an innovation, and every innovation is misguidance. The Prophet ﷺ said, “Whoever introduces into this matter of ours something that does not belong to it, it is rejected.” (1) In another wording: “Whoever performs a deed that is not in accordance with our affair, it is rejected.” (2)

Likewise, any policy or ruling among people that Allah and His Messenger have not authorized is the rule of the tāghūt, the rule of pre-Islamic ignorance: “Is it the judgment of ignorance they seek? Yet who is better than Allah in judgment for a people who are certain?” (5:50).

Declaring things lawful or unlawful is also the exclusive right of Allah; no one may share in it. He said: “Do not eat of that over which the name of Allah has not been pronounced, for that is heinous. Indeed, the devils whisper to their allies so that they may argue with you; and if you obey them, you will surely be idolaters.” (6:121)