Tafsir of At-Takweer 81:24

{And he is not}—that is, the Messenger of Allah, may Allah exalt his mention—{regarding the Unseen}—regarding what he reports of the revelation (wahi) sent to him and other matters of the Unseen—{withheld (bi-danin)}. This is derived from al-dan—with the dad either kasra or fatha—meaning stinginess. That is, he is not stingy; he does not withhold the revelation, nor does he fall short in conveying, teaching, and bestowing all the knowledge for which [the people] are prepared, unlike the soothsayers, for they do not disclose what they claim to know except in exchange for a fee.

Ibn Mas‘ud, Ibn Abbas, Zayd ibn Thabit, Ibn Umar, Ibn al-Zubayr, Aisha, Umar ibn Abd al-Aziz, Ibn Jubayr, Urwah, Hisham ibn Jundub, Mujahid, and others—and from the seven readers, the two grammarians [Abu Amr and Al-Kisa'i] and Ibn Kathir—read it as bi-zannin with a za’ (ظنين). That is, one who is accused (muttaham), derived from al-zinnah (the accusation). This corresponds to the previous description of him being “trustworthy” (amin). It is also said that it means: weak in strength regarding the conveyance of the revelation, taken from the saying, “a zunun well,” meaning one with little water.

The former reading [with the dad] is more famous, yet this reading [with the za’] is considered superior for the context, because the disbelievers accused him—may Allah exalt his mention—and refuting an accusation is more appropriate than refuting stinginess. Furthermore, the word "accusation" takes the preposition "bi-" followed by "‘ala" (accused of), unlike "stinginess," which is not used with "‘ala" except by implying the meaning of greed or the like. However, Al-Tabari said that all the copies of the mushafs are written with the dad. Perhaps he meant the widely circulated mushafs, for they stated that the mushaf of Ibn Mas‘ud was written with the za’.

Furthermore, this does not contradict the statement of Abu Ubaydah that in the ancient script, the za’ and the dad do not differ except by a slight mark on the head of one of them over the other, which can be easily confused, as is not hidden. The difference between the dad and the za’ in articulation is that the dad originates from the root of the edge of the tongue and the adjacent molars, from the right or left side of the tongue, and some are able to articulate it from both sides. The za’ originates from the tip of the tongue and the roots of the upper incisors.

There is disagreement regarding whether substituting one for the other invalidates the prayer or not. It is said that it does invalidate it, based on analogy; this is reported in al-Muhit al-Burhani from the majority of the scholars, and in al-Khulasah from Abu Hanifah and Muhammad. It is also said that it does not, based on juristic preference (istihsan); this is reported in the latter work from the majority of the scholars, such as Abu Muti‘ al-Balkhi and Muhammad ibn Salamah. A group has stated that if it is possible to distinguish between them, and one does so intentionally—being a case where it was not recited in that manner, as is the case here—and it changes the meaning, then the prayer is invalidated; otherwise, it is not. This is due to the difficulty of distinguishing between them, especially for non-Arabs. Many of them converted to Islam in the first era, and it was not reported that the Companions urged them to distinguish between them or taught them to do so; had it been mandatory, they would have done it. This is the view that should be relied upon and issued as a fatwa. Some have collected the words whose meaning does not change whether written with a dad or a za’ in a small treatise. He has done well in that, so let it be consulted, for it is important.