Tafsir of Saba' 34:29

"It has been recited: Mīʿād yawm (a promise of a day), Miʿyād yawm, and Mīʿād yawman."

• The Mīʿād: It is a noun of time or place for a promise. Here, it refers to time. The evidence for this is the reading Mīʿād yawm, where "the day" is an appositive (badal) to it.
• If you ask: What is the interpretation of the genitive construction (iḍāfa) to "day," or the accusative case (naṣb) of "day"?
• I say: As for the genitive, it is an iḍāfa of clarification (tabyīn), just as you say "a piece of cloth" (suḥq thawb) or "a camel for irrigation" (baʿīr sāniya).
• As for the accusative (yawman): It is for the purpose of magnification (taʿẓīm) by implying a verb. Its estimation is: "You have a promise—I mean a day," or it is intended as "a day whose description is such and such." It is also permissible for it to be in the nominative case (rafʿ) for the same purpose of magnification.
• If you ask: How does this serve as an answer to their question?
• I say: They did not ask about that out of a desire for guidance, but rather out of obstinacy and denial. Therefore, the answer came in the form of a threat, matching the nature of their question, which was posed in the spirit of denial and stubbornness. It signifies that they are being watched for a day that will take them by surprise, from which they will be unable to delay or hasten.

{And those who disbelieved say, "We will never believe in this Qur'an nor in that which was before it." But if you could see when the wrongdoers are detained before their Lord, refuting one another in speech. Those who were oppressed will say to those who were arrogant, "If not for you, we would have been believers."}