If only they [i.e. the People of the Book] had stood fast by the Law, the Gospel, and all the revelation that was sent to them from their Lord, they would have enjoyed happiness from every side. (surah 5:69)

Say: "O People of the Book! Ye have no ground to stand upon unless ye stand fast by the Law, the Gospel, and all the revelation that has come to you from your Lord." (surah 5:71)