Az-Zumar 39:23 الله نزل احسن الحديث كتابا متشابها مثاني تقشعر منه جلود الذين يخشون ربهم ثم تلين جلودهم وقلوبهم الى ذكر الله ذالك هدى الله يهدي به من يشاء ومن يضلل الله فما له من هاد ٢٣

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.