Tafsir of Az-Zukhruf 43:88

{And his saying, "O my Lord..."}

It is recited with the three vowel marks (fatḥah, kasrah, ḍammah). Regarding the accusative (naṣb), al-Akhfash suggests it is linked to: "Or do they think that We do not hear their secrets and their private conversations?"—meaning: "And [We hear] his saying." It is also reported from him: "And He said his saying."

Al-Zajjāj links it to the position of "the Hour" (as-sāʿah), similar to saying: "I marveled at the striking of Zayd and [the striking of] ʿAmr." The genitive (jarr) is linked to the word "the Hour" itself, while the nominative (rafʿ) is treated as an inceptive (subject), with the following clause serving as the predicate.

Some permit linking it to "the knowledge of the Hour" by assuming an omitted genitive construct (muḍāf), meaning: "With Him is the knowledge of the Hour and the knowledge of his saying." However, what they have stated is not strong in meaning, given the inappropriate interruption between the conjunct and the conjunction, and the dissonance in the arrangement.

The strongest and most sound interpretation is that the genitive and accusative are based on the elision of a particle of oath, and the nominative is based on their expressions like: "By God" (ayman Allāh), "By the trust of God," "By the oath of God," and "By your life." Thus, His saying: {Indeed, these are a people who do not believe} is the response to the oath. It is as if it were said: "And I swear by his saying, 'O my Lord'—or, 'His saying, O my Lord, is my oath—that these are a people who do not believe."

{So turn away from them} Meaning: Turn away from their invitation, having despaired of their belief, and bid them farewell and leave them.

{And say, "Peace"} Meaning: I am safe from you, and I am leaving you.

{But they are going to know} A threat from God to them and a consolation for His Messenger, peace and blessings be upon him. The pronoun in {his saying} refers to the Messenger of God, peace and blessings be upon him. God swearing by his saying is an exaltation of him and a glorification of his supplication and his turning to Him.

From the Prophet, peace and blessings be upon him: "Whoever recites Surah az-Zukhruf will be among those to whom it is said on the Day of Resurrection: 'O My servants, no fear will there be concerning you this Day, nor will you grieve. Enter Paradise, without account.'"