Why did Allah Almighty describe the oath by "the settings of the stars" as a "great oath"?

The exegetes (mufassirun) differed concerning the meaning of the Almighty's saying: "by the setting-places of the stars" (bi-mawāqi‘ al-nujūm). Some of them held that it refers to the places where stars fall when they set, or their positions and stations in the sky, or their dispersion on the Day of Resurrection, indicating thereby their significance in demonstrating the Creator's greatness and power. Others maintained that what is meant is the times of the piecemeal revelation of the Holy Qur'an, supporting this view by arguing that the pronoun in "Indeed, it is a Qur'an" refers to what is understood from "mawāqi‘ al-nujūm." The exegetes affirmed the profound significance of this oath, whether it refers to the revelation of the Qur'an or the known stars, due to the implications it carries regarding God's greatness, power, and wisdom.