According to search-discovered classical Islamic scholarship, the act of fabricating a lie against Allah (Iftira' al-kadhib 'ala Allah) is unequivocally presented in the Quran as the pinnacle of injustice and wickedness. Across numerous verses, including 6:93, 7:37, and 61:7, the Quran poses a powerful rhetorical question: 'And who is more unjust (adhlam) than one who invents a lie about Allah or denies His signs?' The great exegete Ibn Kathir explains this signifies that no act of wrongdoing is greater. This ultimate sin encompasses several forms: claiming to receive revelation when none was given, attempting to produce something similar to the Quran, denying the authentic message of God's true prophets, and usurping divine authority by legislating in matters of lawful and unlawful without permission. Al-Tabari's linguistic analysis of 'iftira' confirms a deliberate act of forgery against the divine. The synthesis of these verses establishes that false prophecy is not merely a lie, but a fundamental corruption of the sacred bond between the Creator and creation, which misleads humanity and constitutes an unforgivable transgression in the absence of repentance.