سورة الأنعام

Ali ibn Ibrahim (may Allah have mercy on him): This word of Allah: وَ مَنْ أَظْلَمُ مِمَّنِ افْتَری عَلَی اللهِ کَذِباً أَوْ کَذَّبَ بِآیاتِهِ إِنَّهُ لا یُفْلِحُ الظَّالِمُونَ [And who is more unjust than he who forges a lie against Allah or gives the lie to His signs; indeed, the wrongdoers will not succeed] is [among] the muhkam [decisive] verses.

The Prophet (peace be upon him and his family): Whoever interprets the Qur'an by his own opinion [and pays no heed to the rational and transmitted evidence of interpretation, or does not possess the qualifications of a mufassir] has forged a lie against Allah.