Rahmatan min rabbika innahu huwa assameeAAu alAAaleem (surah Ad Dukhaan: 6)

Tafseer Tafheem-ul-Quran by Syed Abu-al-A'la Maududi

(44:6) as a Mercy from your Lord. *4 Surely He is All-Hearing, All-Seeing, *5

Rahmatam mir rabbik; innahoo Huwas Samee`ul `Aleem

*4) That is, "It was not only a demand of wisdom to send a Messenger with. this Book but also of Allah's mercy, for He is the Providence, and Providence requires that not only should arrangements be made for nourishing the servants' bodies but they should also be afforded right guidance by knowledge, that they should be made aware of the distinction between right and wrong and that they should not be left wandering in darkness."
*5) The object of mentioning these two attributes of AIlah in this context is to warn the people of the truth that He alone can give correct knowledge for He alone knows aII the realities. Not to speak of one ntan, even if aII men join to determine a way of lift for themselves, there can be no guaranty of its being the right way, for even the whole of mankind together cannot become all-hearing and all-knowing. It does not lie in its power to comprehend aII those realities whose knowledge is essential for determining a correct way of life. This knowledge is only with AIlah: He alone is All-Hearing and AII-Knowing. Therefore, He alone can tell what is guidance for Tnan and what is falsehood, what is the Truth and what is wrong, what is good and what is evil.