Al-An'am 6:114

أَفَغَيۡرَ ٱللَّهِ أَبۡتَغِي حَكَمٗا وَهُوَ ٱلَّذِيٓ أَنزَلَ إِلَيۡكُمُ ٱلۡكِتَٰبَ مُفَصَّلٗاۚ وَٱلَّذِينَ ءَاتَيۡنَٰهُمُ ٱلۡكِتَٰبَ يَعۡلَمُونَ أَنَّهُۥ مُنَزَّلٞ مِّن رَّبِّكَ بِٱلۡحَقِّۖ فَلَا تَكُونَنَّ مِنَ ٱلۡمُمۡتَرِينَ 114

[Say], "Then is it other than Allah I should seek as judge while it is He who has revealed to you the Book 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