ولوﻻ فضل الله عليك ورحمته لهمت طايفة منهم أن يضلوك وما يضلون إﻻ أنفسهم وما يضرونك من شيء وأنزل الله عليك الكتاب والحكمة
Had not the grace of Allah and His mercy been upon you, a party of them would certainly have made a decision to mislead you, but they mislead none except their own selves, and no harm can they do to you in the least. Allah has sent down to you the Book, and the Hikmah,
وعلمك ما لم تكن تعلم
and taught you that which you knew not,
before this revelation was sent down to you.
Similarly, Allah said,
وكذلك أوحينا إليك روحا من أمرنا ما كنت تدرى ما الكتب
And thus We have sent to you (O Muhammad) a Ruh (a revelation, and a mercy) of Our command. You knew not what is the Book) until the end of the Surah. (42:52-53)
Allah said,
وما كنت ترجو أن يلقى إليك الكتب إﻻ رحمة من ربك
And you were not expecting that the Book (this Qur'an) would be sent down to you, but it is a mercy from your Lord. (28:86)
So Allah said;
وكان فضل الله عليك عظيما
And ever great is the grace of Allah unto you (O Muhammad)