By "calling it to witness", i.e., by speaking of the Day of Resurrection as if it had already occurred, the above phrase is meant to convey the certainty of its coming.
Malik Quran Translation
I swear by the Day of Resurrection,
Yusuf Ali Quran Translation
I do call to witness the Resurrection Day; 5809
Yusuf Ali Translation Note Number :
Cf. lxx. 40, and n. 5700. Here the point to be enforced is understood. The appeal is made to two considerations: (1) That every act has to be accounted for, and evil must have its recompense at the Resurrection; and (2) that man's own spirit has a conscience which would reproach him for sin, if he did not suppress that inner voice.
