Tafsir of Sad 38:53

(That is, for the sake of the Day of Reckoning, for what they have been promised is on account of their obedience and their righteous deeds, which become manifest upon the reckoning. Thus, it is as if [the reward] is upon [the day], because the fulfillment of the promise is contingent upon it; therefore, the attribution to the day of reckoning is metaphorical. It is also permitted that the [Arabic preposition] lam bears the meaning of "after," as in the phrase: "written after five days had passed from Jumada al-Akhirah," for example, and this interpretation is less burdensome. Ibn Kathir and Abu ‘Amr read [the verb] as yuwa‘adun (they are promised) with a third-person prefix (ya). According to the recitation of the majority using the second-person prefix (ta), there is a shift in address (iltifat).)