Surah Yunus, Verse 94

فَإِن كُنتَ فِي شَكّٖ مِّمَّآ أَنزَلۡنَآ إِلَيۡكَ فَسۡـَٔلِ ٱلَّذِينَ يَقۡرَءُونَ ٱلۡكِتَٰبَ مِن قَبۡلِكَۚ لَقَدۡ جَآءَكَ ٱلۡحَقُّ مِن رَّبِّكَ فَلَا تَكُونَنَّ مِنَ ٱلۡمُمۡتَرِينَ٩٤

fa-in kunta fī shakkin mimmā anzalnā ilayka fasali alladhīna yaqraūna l-kitāba min qablika laqad jāaka l-ḥaqu min rabbika falā takūnanna mina l-mum'tarīna

So if you are in doubt, [O Muḥammad], about that which We have revealed to you, then ask those who have been reading the Scripture before you. The truth has certainly come to you from your Lord, so never be among the doubters.