اَللّٰهُ نَزَّلَ اَحْسَنَ الْحَدِيْثِ كِتٰبًا مُّتَشَابِهًا مَّثَانِيَۙ تَقْشَعِرُّ مِنْهُ جُلُوْدُ الَّذِيْنَ يَخْشَوْنَ رَبَّهُمْ ۚ ثُمَّ تَلِيْنُ جُلُوْدُهُمْ وَقُلُوْبُهُمْ اِلٰى ذِكْرِ اللّٰهِ ۗذٰلِكَ هُدَى اللّٰهِ يَهْدِيْ بِهٖ مَنْ يَّشَاۤءُ ۗوَمَنْ يُّضْلِلِ اللّٰهُ فَمَا لَهٗ مِنْ هَادٍ ( الزمر: ٢٣ )
Allahu nazzala ahsanal hadeesi Kitaabam mutashaa biham masaaniy taqsha'irru minhu juloodul lazeena yakhshawna Rabbahum summa taleenu julooduhum wa quloo buhum ilaa zikril laah; zaalika hudal laahi yahdee bihee mai yashaaa'; wa mai yudlilil laahu famaa lahoo min haad (az-Zumar 39:23)
Allah has sent down the best statement: a consistent Book wherein is reiteration. The skins shiver therefrom of those who fear their Lord; then their skins and their hearts relax at the remembrance [i.e., mention] of Allah. That is the guidance of Allah by which He guides whom He wills. And one whom Allah sends astray – for him there is no guide. (Az-Zumar  : 23)
1 Mufti Taqi Usmani
Allah has sent down the best discourse, a book containing subjects resembling each other, mentioned again and again, shivered from which are the skins of those who have awe of their Lord. Then, their skins and their hearts become soft enough to tend to the remembrance of Allah. This is the Guidance of Allah with which He brings to the right path whomsoever He wills. As for the one whom Allah lets go astray, for him there is no one to guide.