يَوْمَ هُم بَٰرِزُونَ لَا يَخْفَىٰ عَلَى ٱللَّهِ مِنْهُمْ شَىْءٌ لِّمَنِ ٱلْمُلْكُ ٱلْيَوْمَ لِلَّهِ ٱلْوَٰحِدِ ٱلْقَهَّارِ
"On that day they will be out in the open; nothing of theirs will be hidden from God. 'Whose is the dominion today?' — 'God's, the One, the Qahhār.'"
There is a question in the verse and its answer comes immediately after — but neither side is identified.
The most widespread explanation in the classical commentaries is that both the question and the answer come from the same place: since no one is left to answer, the question receives its own answer. I transmit this as an explanation that is transmitted.
بَٰرِزُون — root ب-ر-ز: to come out into the open, to emerge into view. Barāz — open ground, empty flat land. The word carries the fact that no place is left to hide in.
The choice of attribute is worth recording: in the answer to the question "whose is the dominion?" two attributes are given — al-wāḥid (the One) and al-qahhār. That is, the question of whose the dominion is gets answered both by oneness and by overpowering.