يَوْمَ نَبْطِشُ ٱلْبَطْشَةَ ٱلْكُبْرَىٰٓ إِنَّا مُنتَقِمُونَ
The root was treated at length in al-Burūj and this verse was already cited there. I do not repeat it. The summary of that record:
"Baṭsh: to grasp a thing violently and harshly, to spring upon it and seize it. The word describes the movement of the hand — clawing, snatching, taking hold and not letting go. […] The three elements the word carries: suddenness, harshness, not letting go."
And one thing recorded in the al-Burūj discussion must be carried straight over here: the same root occurs in the Qurʾān as the act of tyrants as well — "And when you seize, you seize like tyrants" (al-Shuʿarāʾ 26/130).
The principle established in al-Burūj was this: the verdict is announced in the language of the crime.
One — the absolute object. Nabṭishu'l-baṭshata: the verb is reinforced with its own verbal noun. In Arabic this structure (mafʿūl muṭlaq) makes the verb certain, and when it takes an adjective it qualifies it.
Two — the adjective: al-kubrā. The feminine of the elative: "the greatest". There is a scale, then — there are lesser seizings too, and this is the greatest of them.
And this is the second centre of the disagreement below: if the lesser seizings are those that happen in this world, then the "greatest" must be somewhere else.
Three — innā muntaqimūn. The root ن-ق-م: to find a thing foul and reject it, to feel displeasure. Niqma — the penalty given as the counterpart of that displeasure.
The difference between the word and the English "vengeance" must be recorded, and this is a point the lexicographers dwell on too: in English, vengeance is the satisfying of a personal anger. In the Arabic root, what stands at the centre is finding a thing unacceptable. Naqima ʿalayhi — he reproached him, he found him foul.
The core of the word, that is, is not emotion but judgement: a thing has been rejected, and its counterpart is being given.
I record this as my own reading, and its ground is the lexicographers' definition of the root. And the pattern supports it too: muntaqimūn is a plural active participle — it reports an attribute, not a moment of anger.