Translation of the verse 42 from Surah Fussilat : Number of verses 54 - - page 481 - Part 24.
Falsehood cannot come to it from before it or behind it (it is) sent down by the All-Wise, Worthy of all praise (Allah).
Falsehood cannot approach it from before it or from behind it; [it is] a revelation from a [Lord who is] Wise and Praiseworthy.
(41:42) Falsehood may not enter it from the front or from the rear. *52 It is a revelation that has been sent down from the Most Wise, the Immensely Praiseworthy.
*52) "Falsehood . . . . from before it" means that none can succeed in proving anything wrong or any teaching false in the Qur'an by making a frontal attack on it; . . . . nor from behind it" means that nothing can be discovered till Resurrection which may be opposed to the truths and realities presented by the Qur'an; no new science, if it is really a "science", can be propounded, which may contradict the knowledge contained in the Qur'an; no new experiment or observation can be made to prove that the guidance given to man by the Qur'an in respect of the beliefs, morality, law, civilization or culture, and economic, social and political lift is wrong. That which this Book has declared as the Truth can never be proved to be falsehood and that which it has declared as falsehood can never be proved to be the truth. Furthermore, it also means that whether falsehood makes a frontal attack, or makes a surprise attack by deception, it cannot defeat the message which the Qur'an has brought. In spite of all sorts of open and secret machinations of the opponents the message will spread and none shall be able to defeat and frustrate it.