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

Allâh has sent down the Best Statement, a Book (this Qur’ân), its parts resembling each other (in goodness and truth) (and) oft-repeated. The skins of those who fear their Lord shiver from it (when they recite it or hear it). Then their skin and their heart soften to the remembrance of Allâh. That is the guidance of Allâh. He Guides therewith whom He wills; and whomever Allâh sends astray, for him there is no guide.