Tafsir of Qaf 50:28

(He says): This is an initiation [of a sentence] based on a question arising from what preceded it, as if it were said: "What did Allah—Exalted be He—say?" It was replied: The Almighty said: (Do not dispute before Me), meaning: in the station of reckoning and recompense, for there is no benefit in that. (While I had already sent the threat to you) concerning tyranny in the abode of acquisition [the worldly life], through My Books and upon the tongues of My Messengers. Do not, therefore, covet salvation from it by means of the false excuses you are offering.

The sentence is a state (hal) containing the justification for the prohibition. The meaning of 'knowledge' is observed here to achieve the correlation required by the hal, meaning: "Do not dispute before Me, while knowing that I had already sent the threat to you, as I said to Iblis: (I will surely fill Hell with you and those who follow you among them), yet you followed him, turning away from the truth."

The ba [in bi-al-wa'id] is either augmentative or transitive, given that qaddama can have the meaning of 'to precede,' and when it is intransitive, it is made transitive by the ba. It is also possible that qaddama refers to the saying of the Almighty [elsewhere in the Quran].