Qur'an 6:114

أَفَغَيْرَ ٱللَّهِ أَبْتَغِى حَكَمًا وَهُوَ ٱلَّذِىٓ أَنزَلَ إِلَيْكُمُ ٱلْكِتَـٰبَ مُفَصَّلًا ۚ وَٱلَّذِينَ ءَاتَيْنَـٰهُمُ ٱلْكِتَـٰبَ يَعْلَمُونَ أَنَّهُۥ مُنَزَّلٌ مِّن رَّبِّكَ بِٱلْحَقِّ ۖ فَلَا تَكُونَنَّ مِنَ ٱلْمُمْتَرِينَ

“[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.”

Al-An'aam 6:114 · Saheeh International