Tafsir of At-Takweer 81:23

{And he has already seen him at the clear horizon} The Messenger of Allah (ﷺ) saw Gabriel at the clear horizon, which is the highest point of the sunrise.

{And he is not} Muhammad (ﷺ) is not, regarding what he conveys of the unseen—such as seeing Gabriel, the revelation, and other matters—{a denier (bi-ḍanīn)}.

• Bi-ḍanīn (with ḍād): Meaning one who is accused (from ẓinna, which is accusation).
• Bi-ẓanīn (with ẓāʾ): Meaning one who is stingy (from ḍann, which is miserliness). It means he does not withhold the revelation, nor does he conceal any part of it, nor does he refuse to teach it when asked.

This word appears with a ẓāʾ in the codex of ʿAbd Allāh and with a ḍād in the codex of Ubayy, and the Messenger of Allah (ﷺ) used to recite it both ways.

A Note on Phonetics: Mastering the distinction between the ḍād and the ẓāʾ is mandatory. A reciter must know their points of articulation, as most non-Arabs fail to distinguish between them, or do so incorrectly. There is a vast difference between them:

• The Ḍād: Its articulation point is the root of the side of the tongue and the adjacent molars, from either the right or left side. ʿUmar ibn al-Khaṭṭāb (ra) was ambidextrous and would articulate the ḍād from both sides of his tongue. It is one of the shajariyyah (palatal) letters, a sibling to the jīm and shīn.
• The Ẓāʾ: Its articulation point is the tip of the tongue and the roots of the upper incisors. It is one of the dhawliqiyyah (dental/tip) letters, a sibling to the dhāl and thāʾ.

If the two letters were the same, there would not be two distinct readings for this word, nor would there be a disagreement between two mountains of knowledge and recitation, nor would the meaning, derivation, and structure differ. If you ask: "What if a person replaces one letter with the other in prayer?" I say: It is like replacing the dhāl with the jīm, or the thāʾ with the shīn, because the difference between the ḍād and the ẓāʾ is as great as the difference between their respective siblings.

{And it is not} The Qurʾan is not {the word of a cursed devil}—that is, the word of those who steal a hearing or the whisperings they cast to their allies among the soothsayers.

{So where are you going? It is but a reminder to the worlds. For whoever among you wills to take a straight path. And you do not will except that Allah wills—Lord of the worlds.}