Tafsir of Al-Burooj 85:9

(He to whom belongs the dominion of the heavens and the earth): This is to indicate the basis of their faith. As for His, the Exalted’s, saying: (And Allah is Witness over all things), it is a promise to them and a threat to their tormentors. For the knowledge of Allah, may His majesty be glorified—which encompasses all the attributes of Majesty and Beauty—regarding all things (among which are the deeds of both groups), necessitates the providing of recompense for each of them. Because it is a concluding statement (tadhil) to that, and independence is more fitting for it, the Majestic Name was used rather than a pronoun.