See ⦗1⦘ how the oath ⦗2⦘ is introduced with a particle of negation; then the very opposite of what they alleged is affirmed, so that the verse conveys the meaning ⦗3⦘: “The matter is not as they claim; rather, it is a noble Quran.”

For that reason He states both the negation and the affirmation explicitly in His words:
“No! I swear by the retreating stars, ⦗15⦘
those that run and disappear, ⦗16⦘
by the night as it darkens, ⦗17⦘
and the dawn as it breathes—⦗18⦘
indeed, it is certainly the word of an honored messenger. ⦗19⦘” ⦗4⦘

The same occurs in His saying:
“No! I swear by the Day of Resurrection, ⦗1⦘
and no! I swear by the self-reproaching soul. ⦗2⦘
Does man think that We shall never gather his bones? ⦗3⦘
Yes indeed! We are able even to reshape his very fingertips. ⦗4⦘” ⦗5⦘

The point is that beginning an oath with the negative particle enhances the force of what is sworn to, confirms it, and strongly denies its negation.

The second level of emphasis lies in the oath itself.

The third lies in the object sworn by—His swearing by Himself rather than by any of His creatures. Exalted is He: at times He swears by Himself, and at times by elements of His creation.

The fourth level of emphasis is produced by the removal of all hesitation and the presence of full submission. ⦗6⦘