﴿ وَأَنِ ٱحْكُم بَيْنَهُم بِمَآ أَنزَلَ ٱللَّهُ وَلَا تَتَّبِعْ أَهْوَآءَهُمْ وَٱحْذَرْهُمْ أَن يَفْتِنُوكَ عَنۢ بَعْضِ مَآ أَنزَلَ ٱللَّهُ إِلَيْكَ ۖ فَإِن تَوَلَّوْا۟ فَٱعْلَمْ أَنَّمَا يُرِيدُ ٱللَّهُ أَن يُصِيبَهُم بِبَعْضِ ذُنُوبِهِمْ ۗ وَإِنَّ كَثِيرًۭا مِّنَ ٱلنَّاسِ لَفَٰسِقُونَ ﴾

“Hence, judge between the followers of earlier revelation in accordance with what God has bestowed from on high, and do not follow their errant views; and beware of them, lest they tempt thee away from aught that God has bestowed from on high upon thee. And if they turn away [from His commandments], then know that it is but God's will [thus] to afflict them for some of their sins: for, behold, a great many people are iniquitous indeed.”

The Quran and other Divine Scriptures are not separate books. They are the different editions of a single Book of God which has been named al-kitab here. All editions of the Book revealed by God were one and the same as regards content. However, the bearers of the previous scriptures could not in the later periods preserve them in their original form. Therefore, God revealed His Book (muhaymin) i.e. the Quran, the authentic expression of His will, — a touchstone which reveals which sections of the other scriptures have retained their original form and which have been changed.