Qur'an 6:114 · Al-An'aam

أَفَغَيْرَ ٱللَّهِ أَبْتَغِى حَكَمًۭا وَهُوَ ٱلَّذِىٓ أَنزَلَ إِلَيْكُمُ ٱلْكِتَٰبَ مُفَصَّلًۭا ۚ وَٱلَّذِينَ ءَاتَيْنَٰهُمُ ٱلْكِتَٰبَ يَعْلَمُونَ أَنَّهُۥ مُنَزَّلٌۭ مِّن رَّبِّكَ بِٱلْحَقِّ ۖ فَلَا تَكُونَنَّ مِنَ ٱلْمُمْتَرِينَ

(114) [Say], "Then is it other than Allāh I should seek as judge while it is He who has revealed to you the Book [i.e., the Qur’ān] explained in detail?" And those to whom We [previously] gave the Scripture know that it is sent down from your Lord in truth, so never be among the doubters.