And if you speak aloud, then verily, He knows the secret and that which is yet more hidden.
This means that He Who revealed this Qur'an, has also created the high heavens and the earth and He knows that which is secret and what is even more hidden.
As Allah says,
قُلْ أَنزَلَهُ الَّذِى يَعْلَمُ السِّرَّ فِى السَّمَـوَتِ وَالاٌّرْضِ إِنَّهُ كَانَ غَفُوراً رَّحِيماً
Say;"It has been sent down by Him Who knows the secret of the heavens and the earth. Truly, He is Oft-Forgiving, Most Merciful." (25;6)
Ali bin Abi Talhah reported that Ibn Abbas said,
يَعْلَمُ السِّرَّ وَأَخْفَى
(He knows the secret and that which is yet more hidden),
"The secret is what the son of Adam hides within himself, and
وَأَخْفَى
(that which is yet more hidden),
is the deeds of the son of Adam, which are hidden before he does them.
Allah knows all of that. His knowledge encompasses that which has passed and that which is in the future and it is one, complete knowledge.
In this regard, all of the creatures are as one soul to Him. That is the meaning of His statement,
مَّا خَلْقُكُمْ وَلَا بَعْثُكُمْ إِلاَّ كَنَفْسٍ وَحِدَةٍ
The creation of you all and the resurrection of you all are only as a single person. (31;28)
Concerning Allah's statement,
اللَّهُ لَا إِلَهَ إِلاَّ هُوَ لَهُ الاَْسْمَاء الْحُسْنَى