Certainty and removal of doubt

ذَٰلِكَ ٱلْكِتَـٰبُ لَا رَيْبَ ۛ فِيهِ ۛ هُدًى لِّلْمُتَّقِينَ

This is the Book about which there is no doubt, a guidance for those conscious of Allāh -

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

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.