Tafsir of Ash-Shu`ara' 26:188

(He said, "My Lord is most knowing of what you do.")

Meaning: He, the Exalted, is more knowing of your deeds, such as disbelief and acts of disobedience, and of the punishment you deserve for them. He will inevitably send it down upon you according to what you deserve, at its appointed time, without fail.