The author may God have mercy upon him said “Allāh revealed that His knowledge encompasses everything.

The explanation:  Allāh knows everything, nothing is hidden from him.  Allāh’s knowledge has no beginning.  All of His attributes have no beginning and no end and change does not occur upon him.

Allāh revealed the Qur’ān containing verses that are a test for the slaves and so as a result people are divided into two categories.  One category interprets those verses according to what the religion permits and so they are victorious.  Another category misinterprets those verses and therefore perishes.  An example of that is like the verse

الآن خفف الله عنكم وعلم أن فيكم ضعفا

So there are some people who think the meaning of the verse is that Allāh knew something after having not known it and therefore they have blasphemed an explicit blasphemy because they have attributed ignorance to Allāh.

Whoever understands the correct meaning of that verse which is that Now the judgment that used to apply to you which is for one muslim to take on a minimum of 10 non-believers at a time in the battle has been decreased to a minimum of at least 2 non-believers per muslim fighter.  that is because Allāh knew with His eternal knowledge that there is weakness within you.  So whoever understands this correct meaning then such a person has known the truth and has been guided to the unerring path.

Indeed everything that occurs in this universe in the skies and the earth and in land and in sea and what is under the sand is written in the guarded tablet just as At-tirmidhiyy narrated from the Prophet peace be upon him that Allāh ordered the upper pen to write what has occurred and what shall occur until Judgment Day.  The meaning of the saying of the author “Allāh’s knowledge encompasses all” is that He, The Exalted, knows what has existed and what shall exist with His Eternal and Everlasting Knowledge that does not change.