التفسير التبليغي
And they said, "Our Lord, hasten to us our portion before the Day of Account." (16)
The ignorant ones said, as they described the methodology of prophethood: (أَجَعَلَ الْآلِهَةَ إِلَهًا وَاحِدًا إِنَّ هَذَا لَشَيْءٌ عُجَابٌ) "Has he made the gods [into] one God? Indeed, this is a truly astonishing thing!" So they were astonished by the call of the prophetic methodology to the Oneness of Allah, and they disdained the worship of one God.
(عَجِّلْ لَنَا قِطَّنَا) meaning: hasten to us our share of the torment, as a mockery from them of this warning.
(عَجِّلْ لَنَا) hasten to us the warning with which you threaten us, O Muhammad.
Al-Qitt (الْقِطُّ): the portion or share.
At this point, the narrative leaves them and turns to the Messenger (peace and blessings of Allah be upon him) to console him regarding the foolishness of the people, their ill-manners towards Allah, and their hastening of the recompense.
(قَبْلَ يَوْمِ الْحِسَابِ) meaning: which is the Day of Account, in the Muslims' claim, not in our claim.
Source: التفسير التبليغي