Tafsir of Al-Infitar 82:5

This is the response to Idha (when), but it is not that it shall know it at the time of the Resurrection; rather, it shall know it when the records are spread open. This is because it is known that the intended meaning of [the timeframe of Idha] is a single period, starting shortly before the first blast of the Horn and ending with the judgment between the creation, not multiple distinct periods according to the word Idha. It was repeated only to emphasize the magnitude of the calamities contained within it, and the discussion regarding it is the same as that which passed in its counterpart.

The meaning of "what it has put forth and kept back" is: what it sent ahead of good or evil deeds, and what it left behind of a sunnah—whether good or evil—that is practiced after its death. This was stated by Ibn Abbas and Abu Mas'ud. It is also narrated from Ibn Abbas that it means what it put forth of disobedience and what it kept back of obedience; this is the view of Qatada. Others said: what it performed of that which it was tasked with, and what it did not perform of it. Others said: what it sent forth of its wealth for itself, and what it kept back for its heirs. Others said: its first deed and its last. The meaning of its knowledge regarding both is its detailed knowledge, according to what was mentioned previously.