Tafsir of Al-`Ankabut 29:53

(And they urge you to hasten the punishment), meaning the disbelievers of Quraysh urge you to hasten it by way of mockery, challenge, and denial of it, through their saying: "When is this promise?" and their saying: "Rain down upon us stones from the sky or bring us a painful punishment," and similar statements.

(And had it not been for a specified term) which Allah the Exalted had set for their punishment, named, and recorded in the Preserved Tablet, (the punishment would have come to them)—the specific punishment they were hastening. Ibn Jubayr said: The intended meaning of the "term" is the Day of Resurrection, as it is reported that Allah the Exalted promised His Messenger (may Allah bless him and grant him peace) that He would not punish his people with a punishment of total annihilation, and that He would delay their punishment until the Day of Resurrection. Ibn Salam said: The intended meaning is the period between the two blasts of the Trumpet. It has also been said: It refers to the Day of Badr. Others said: It refers to the time of their perishing by their natural lifespans, but this is clearly remote, for they were not being promised their natural death, nor were they seeking to hasten it.

(But it will surely come to them) is an initiating sentence clarifying what was indicated in the previous sentence regarding the coming of the punishment upon the arrival of the term; meaning, and by Allah the Exalted, (it will surely come to them)—the punishment designated for them—when the term arrives, (suddenly), meaning unexpectedly, (while they do not perceive), meaning while they are unaware of its arrival.

Perhaps the intent behind it coming "suddenly" is that it will not occur by way of hastening it in accordance with their demand and the answering of their request—for that would be an arrival according to their opinion and perception—but rather, it will come to them while they are heedless and feel secure, not having it in mind, as was the case with some of the punishments that befell certain nations, coming upon them while they were asleep or in the forenoon while they were playing. This is because the coming of the punishment of the Hereafter or the punishment of the Day of Badr is not of that nature, as stated by some. Others said: Its arrival is indeed "sudden" in the sense that it is unexpected by them; and the coming of the punishment of the Hereafter and the like is likewise unexpected for them because of their denial of the Resurrection, or their belief in the intercession of their gods to ward off punishment from them. The same applies to the coming of the punishment of the Day of Badr, because, due to their arrogance, they did not anticipate the victory of the Muslims, nor did it ever cross their minds, as is explained in the chronicles.