Tafsir of Saba' 34:28

{Except as a kāffah (comprehensive/all-encompassing) to mankind} Meaning: His mission is general and encompasses them all. Because if it includes them, it suffices to ensure that none of them are left outside of it.

Al-Zajjaj said: The meaning is "We sent you as one who gathers mankind" in warning and notification. He made it a ḥāl (state) of the kāf (in arsalnāka). According to this, the tā’ in kāffah must be for intensification, like the tā’ in rāwiyah (one who narrates much) or ‘allāmah (one who knows much).

As for the one who makes it a ḥāl of the genitive (the kāf in arsalnāka) while placing it before it—he has erred. For the precedence of the ḥāl of a genitive over the genitive itself is as impossible as the precedence of the genitive over the preposition. You see many who commit this error, and they do not stop there; they add to it by claiming the lām (in lin-nās) means ilā (to). The first error cannot be sustained for them without the second, so they are forced to commit both errors.

{And they say, "When is this promise, if you should be truthful?" * Say, "For you is the appointment of a Day which you cannot delay an hour, nor can you advance it."}