And it is He who created the heavens and earth in truth. And the day [i.e., whenever] He says, "Be," and it is, His word is the truth.1 And His is the dominion [on] the Day the Horn is blown. [He is] Knower of the unseen2 and the witnessed;3 and He is the Wise, the Aware.
Translation: Saheeh International (English)
1 When interpreted as the "Day" (of resurrection), the sentence would read: "And the Day He says, 'Be,' and it is, His word will be the truth."
2 That which is absent, invisible, or beyond the perception of the senses or of the mind and therefore is unknown to man, except for what Allāh chooses to reveal.
3 What is present, visible and known to man. The knowledge of Allāh (subḥānahu wa taʿālā) includes the reality of all things and all occurrences, no matter how they might appear to human beings.
He is the One Who created the heavens and the earth for a purpose. On the day when Allah will say to something ‘Be’ and it will become, refers to the Day of Rising when Allah will say ‘Rise’ and they will all rise. His word is the truth that will most certainly occur. On the Day of Rising, when the angel Isrāfīl will blow the trumpet for a second time, all control will be Allah’s alone. He knows what is hidden and what can be seen. He is Wise in His creating and handling of matters. He is Aware about the hidden just as He knows the apparent, and nothing is hidden from Him.