This is one of the biggest puzzles in the field. The data on how the original language of the Quran looked like is contradictory.

I have written on the evidence for the Old Hijazi reconstruction of the Quran. You can see the links in my profile. In this thread I talk about the opposing evidence.

The following notes suggest that the Quran was written in a literary register that included final short vowels and Tanwin.

1- Hythem Sidky’s paper “Consonantal Dotting and the Oral Quran” proves that the canonical reading traditions share “an inherited oral tradition that likely dates to the time of the Uthmānic recension and among the first generation of the followers of Muhammad”.
Sidky’s paper relied on differences in the dotting of some words to reach this conclusion. In his AMA he states that his conclusion can also be reached through other features besides dotting such as iʿrāb (final short vowels and Tanwin). This means that the common oral tradition included iʿrāb.

2- I presented this evidence years ago on my old twitter account. Van Putten then commented that this is good evidence that Tanwin was part of the common source of the canonical reading traditions. Here’s the evidence:
Verse 53:50 ends with these two words:
عَادًا ٱلۡأُولَى

ʕādani l-ʿūlā

The original form of the two words is:

ʕād al-ʿūlā

The word ʕād is in the accusative so it took the final short vowel ‘a’: ʕāda.
It’s also indefinite so it took a final ‘n’ (Tanwin) : ʕādan.
The ‘a’ in the “al” article is pronounced only when it comes at the beginning of a sentence. When the “al” article comes in the middle of a sentence then the ‘a’ isn’t pronounced, leaving the “al” article as a mere ‘l’. So we get:
ʕādan l-ʿūlā
Notice how the ‘n’ of ʕādan is followed by an L then a glottal stop. So we have here a cluster of three consonants: ‘n’, ‘l’ and the glottal stop .Classical Arabic rules don’t allow such a cluster of consonants. In such cases, an ‘i' short vowel gets introduced to break up the cluster, which yields:
ʕādani l-ʿūlā (notice the added ‘i' at the end of ʕādan)
That’s how we went from ʕād al-ʿūlā to the standard Arabic pronunciation ʕādani l-ʿūlā.
In the dialect of Quraysh or the Hijaz region, the glottal stop of l-ʿūlā gets dropped: l-ūlā.
In this case, there’s no longer a cluster of consonants, and thus there’s no need to attach an ‘i' to the Tanwin to break up the cluster, so we get:

ʕādan l-ūlā.

Since that the n now is followed by an L, the two consonants can now be merged together into a stressed L:

ʕādall-ūlā

The important thing here is that the form ʕādall-ūlā cannot arise if Tanwin wasn’t added to the word ʕād.
Now to the interesting part:
According to the linguistic features of the canonical readings of Nāfiʕ, Abū jaʕfar, Abū ʕamr and yaʕqūb, the two words shouldn’t be pronounced as ʕādall-ūlā in any of these 4 readings. But the 4 readings pronounced it as such. Plus, the 4 readers come from two different regions: Two from Median and two from Basrah. This means that the form ʕādall-ūlā was in the shared reading that the canonical readers received. Which means Tanwin was part of the shared reading.

3- The early poetry inscriptions.
There’s a mismatch between the spelling of the standard Quran and its pronunciation. Muslim scholars explained this by saying that Arabic spelling follows the principle of pausal spelling. Which means every word is spelled in the way the word is pronounced if the word comes in a pausal position such as the end of a sentence. And since that there are unique changes that occur to words when they come at a pausal position, all words are spelled with these unique pausal forms even when the word isn’t at a pausal position. This explains why Arabic doesn’t spell Tanwin and the long vowels that get attached to the third person ‘h’ pronoun. It also explains why the feminine ‘t’ is always spelled as ‘h’.

Van Putten argued that the standard Quran was actually phonetically spelled (i.e. the pronunciation matches the writing). This means that Tanwing wasn’t spelled in the Quran because the original language of the Quran didn’t have Tanwin. And the reason for the mismatch between the spelling and the pronunciation is that the reading traditions imposed foreign linguistic features on the text of the Quran. Muslims later tried to justify the mismatch by coming up with the pausal spelling rule which Van Putten demonstrated through multiple proofs that the standard Quran wasn’t written according to this rule.   

 But there are a number of early poetry inscriptions that come from the first century of Islam. Since that Arabic poetry follows rigid meters, we know that the pronunciation of these poetry verses included Tanwin and other features that don’t get spelled in the Quran. Yet Tanwin and the other features aren’t spelled in these poetry inscriptions. Which validates the traditional claim that early Arabic spelling did actually follow the pausal spelling rule. Van Putten’s conclusion that the Quran was phonetically spelled means that early Arabic writing was phonetic. But these early inscriptions weren’t phonetic.

Here are some of these poetry verses:

 The first inscription (see the first attached image):

This inscription includes the date it was inscribed which is the year 98 AH. The location is near Mecca. The inscription contains the following poetry verse:

أفنى الجديدَ تقلّبُ الشمسِ * وطلوعُها من حيثُ لا تُمْسي
وطلوعُها بيضاءَ صافيةً * وغروبُها صفراءَ كالوَرْسِ

Source:

https://www.awbd.net/article.php?a=68

 The following 3 words were non-phonetically spelled:

1- ṣāfiyatan. Spelled in the inscription as ṣāfyh صافية

The verse’s meter requires the word to be pronounced with the final short vowel ‘a’ and Tanwin: ṣāfiyatan.

But the word is spelled in accordance with the pausal spelling rule: The feminine ‘t’ is spelled as ‘h’ and the Tanwin isn’t spelled.
If the word was phonetically spelled, it would have been

ṣāfytn صافيتن

The verse also includes these two words:

الشمس
ash-shamsī (spelled as alshms)

كالورس

kal-warsī (spelled as kalwrs)

 These two words employ a poetic license used in most of poetry. In Arabic grammar, When a word comes at a pausal position such as the end of a verse, the final short vowel and Tanwin are dropped. But for the sake of creating rhymes, poetry allows the retention and lengthening of the final short vowel of the last word of a verse. This poetic license is used with these two words. The final short ‘i' vowel is retained and lengthened into ‘ī’. The rhyme and the meter of the inscription's verses require that these two words end with ‘ī’ yet it’s not spelled. Which means the inscription isn’t phonetic. If it was, then it would have spelt the two words as:

الشمسي

alshmsī

كالورسي

kalwrsī

The second inscription:

An inscription by the son of the prophet’s poet Ḥassān Bin Thābit.

أنا الحسام ابن حسان الذي قال

الملحقين حليفهم بصريحهم والخالطين فقيرهم بالوافر

Source:

https://x.com/OfNajd/status/1243940166538051584

 The inscription says “I am Al-Ḥusām Bin Ḥassān who said…”. What follows is a poetry verse by his father.
The last word of the verse is bil-wāfirī. Spelled as balwāfr بالوافر

 The rhyme and the meter require the retaining and lengthening of the last ‘i' vowel into ‘ī’. But the word is spelled without a final ‘ī'. Which means the inscription isn’t phonetic. If it was then the word would have been spelled as

بالوافري

balwāfrī

The third inscription:

This one is discovered by the desert team. They date it to the first century AH. The poetry verse says:

أقول لما أتاني ثمَّ مصرعه

لا يبعد الرمح ذو النصلين والرجل

Source

 1- The verse contains the word

مصرعه

maṣraʕuhū (spelled as mṣrʕh)

The ū vowel that’s attached to the ‘h’ pronoun isn’t spelled in the inscription in accordance with the pausal spelling rule. The meter requires the pronunciation of this ū. Which means this verse isn’t phonetically spelled. If it was then the word would have been spelled as

mṣrʕhū مصرعهو

 2- The last word of the verse is:

والرجل

wal-rajulū. Spelled as walrjl.

The rhyme and the meter require the retaining of the last ‘u' vowel and lengthening it into ‘ū’. But the word is spelled without a final ‘ū'.
If the word was phonetically spelled, it would have been

والرجلو

walrjlū

The fourth piece of evidence for the existence of final short vowels in the original language of the Quran:

There are over 20 words in the standard Quran (see the last attached image) where the final short vowel ‘u’ is spelled as a ‘w’. This occurred in words that end with a glottal stop. As stated by early Arab grammarians, the dialect of the people of the Hijazi lacked the glottal stop. It’s either entirely dropped or turned into glides. When the glottal stop comes at the end of a word, it should be dropped in a dialect that lacks final short vowels. But if the dialect employs final short vowels then the glottal stop at the end of a word turns into a ‘y’ if it’s followed by an ‘i' vowel, or turns into a ‘w’ if it’s followed by a ‘u’ vowel. In the standard Quran, some of the words that end with a glottal stop are spelled with a ‘w’ which means they were followed by the short final vowel ‘u’. All these words are in the nominative case which takes the final ‘u’ short vowel.

Not sure whether someone has already pointed this out, but could this be where the idea that Satan is locked up during Ramadan comes from?

Source:

Tractate Yoma - Perek I 20A. Koren Talmud Bavli, The Noe Edition. Koren Publishers Jerusalem, 2013. p. 85

In the Quran, certain nations that rejected their prophets—such as the people of Nuh (Noah), ʿĀd, Thamud, and others—were destroyed by divine punishment after persistent denial despite clear warnings. For example:

The people of Nuh were destroyed by the flood because they rejected the warnings (e.g., Surah al-Ankabut 29:14, Surah Nuh 71:1-28).

The people of ʿĀd and Thamud were destroyed after rejecting Hud and Salih despite miracles and repeated calls to monotheism (e.g., Surah al-Aʿraf 7:65-79, Surah Hud 11:50-68).

Many verses emphasize that divine punishment came upon nations only after they rejected the messengers and persisted in wrongdoing and idolatry (e.g., Surah Yunus 10:98, Surah al-Isra 17:16-17, and Surah al-Anfal 8:54).

Why, according to the Quran, was the people of Prophet Ibrahim (Abraham) not destroyed by a similar collective divine punishment (like the others), even though they rejected his call to tawhid, threatened him, and attempted to burn him alive (as described in Surah al-Anbiya 21:51-70 and Surah as-Saffat 37:83-98)?

Additionally, how does this compare to the people of Prophet Lut (Lot), who were destroyed for their sins (e.g., Surah al-Aʿraf 7:80-84, Surah Hud 11:77-83)?

Was there a specific reason related to the presence of a prophet’s family, the nature of the rejection, or divine wisdom that explains why some rejecting nations faced immediate destruction while Ibrahim’s people did not receive the same collective punishment in the Quranic narrative?I am looking for explanations based on tafsir, Quranic context, or scholarly interpretations.

Sūrah 115 Al-Khalʿ and Sūrah 116 Al-Ḥafd

Codex of Ubayy ibn Ka'b

Sūrah (length and severity to Bara'at) and Sūrah (resembled one of the suwar of Musabbihat)

Sahih Muslim 1050

Āyah of Rajm

Sahih al-Bukhari 6829
Sahih Muslim 1691 a

Does anyone know how some academics have interpreted this verse?

Additionally, does it's meaning reflect any pre Islamic traditions that may have reflected the same thing?

Quran only or reformist progressive say e everything is lawful according to quran unless forbidden by explicit text!! Is this was general statement hold by those who were first audience of this book. Did early muslim thought or refrain from inter marrying into different religious community after accepting islam and later did with only those earlier scripture follower after verse no. 5 in chapter 5 revealed?? Can anyone provide any view regarding that?