Everything Small or Large is within the Knowledge of Allah

Allah informed His Prophet that He knows and is well acquainted with all of the affairs and conditions of him and his Ummah and all of creation and its creatures at all times -- during every hour and second. Nothing slips or escapes from His knowledge and observation, not even anything the weight of a speck of dust within the heavens or earth, or anything that is smaller or larger than that. Everything is in a manifest Book, as Allah said:

وَعِندَهُ مَفَاتِحُ الْغَيْبِ لاَ يَعْلَمُهَآ إِلاَّ هُوَ وَيَعْلَمُ مَا فِى الْبَرِّ وَالْبَحْرِ وَمَا تَسْقُطُ مِن وَرَقَةٍ إِلاَّ يَعْلَمُهَا وَلاَ حَبَّةٍ فِى ظُلُمَـتِ الاٌّرْضِ وَلاَ رَطْبٍ وَلاَ يَابِسٍ إِلاَّ فِى كِتَـبٍ مُّبِينٍ

In the fifth verse (61), mention has been made of the all-encompassing knowledge of the most exalted Allah and its unmatched multi-dimensional extensions. The address is to the Holy Prophet ﷺ . He is being told that nothing he does by way of his work or recital of the Qur'an remains hidden from Allah. Similarly, whatever all human beings do remains before Him. And not even a single particle in the heavens and the earth is concealed from Him. Rather, everything is written in the clear Book, that is, the Preserved Tablet (al lawh al-mahfuz).

At this place, as it seems, the wisdom of describing the all-encompassing nature of Divine knowledge is aimed at consoling the Holy Prophet ﷺ that his enemies cannot harm him in any way for he was under the protection of Allah Ta` ala.