Tafsir of Al-A'raf 7:34

{And for every nation is a term} This is a threat to the people of Mecca regarding the punishment that will descend at a term known to God, just as it descended upon the nations [of the past]. It is read: “fa-idhā jā’a ājāluhum” (when their terms come).

{An hour} He said "an hour" because it is the shortest unit of time in common human usage. A person in a hurry says to his companion, "In an hour," meaning the shortest and nearest time.

{O children of Adam, if there come to you messengers from among you, relating to you My verses, then whoever fears God and reforms—there will be no fear concerning them, nor will they grieve. But the ones who denied Our verses and were arrogant toward them—those are the companions of the Fire; they will abide therein eternally.}