Sura Yūnus 10:94

فَإِن كُنتَ فِى شَكٍّ مِّمَّآ أَنزَلْنَآ إِلَيْكَ فَسْـَٔلِ ٱلَّذِينَ يَقْرَءُونَ ٱلْكِتَٰبَ مِن قَبْلِكَ لَقَدْ جَآءَكَ ٱلْحَقُّ مِن رَّبِّكَ فَلَا تَكُونَنَّ مِنَ ٱلْمُمْتَرِينَ

fa-in kunta fī shakkin mimmā anzalnā ilayka fa-sʾali lladhīna yaqraʾūna l-kitāba min qablika la-qad jāʾaka l-ḥaqqu min rabbika fa-lā takūnanna mina l-mumtarīna

If thou wert in doubt as to what We have revealed unto thee, then ask those who have been reading the Book from before thee: the Truth hath indeed come to thee from thy Lord: so be in no wise of those in doubt.