Mary the Erstwhile Messenger
Most, if not all of the more than fifty original inscriptions on the Dome of the Rock are Koranic in origin. It is difficult to say which are not, if any, because Allah's book of revealed truths has gone through a number of revisions and redaction, the last, the so-called Cairo edition, was completed in the 1920s at Al-Azhar University and is the basis of all modern (twentieth, twenty-first century) mainstream translations.
The inscriptions in question are seventh century in origin which, according to Estelle Whelan, writing in the Journal of the American Oriental Society, "have generally being ignored or dismissed because of apparent departures from the 'canonical' text, as represented by the Cairo edition." Including, it would seem, the inscription where Mary, the mother of Jesus, has the status of Messenger.
On the inner octagonal arcade of the Dome of the Rock you can read the following inscription pertaining to Mary's status:
Mary, was only a Messenger of God, and His Word which He conveyed unto Mary, and a spirit from Him. So believe in God and His messengers, and say not 'Three' - Cease!
In the seventh century, Mary was considered a Messenger of Allah, today she is no such thing, and the Cairo edition is clear on the concept.
Estelle Whelan goes on to explain how we got to the Cairo edition (lightly edited to conform to the naming convention used throughout most of this site e.g. al-Madinah changed to Medina):
In the last two decades a controversy has arisen over the period in which the text of Muslim scripture became codified. The traditional Islamic view can be summarized as follows.
Both Abu Bakr (632-34) and Umar (634-44) made efforts to gather together the scraps of revelation that had been written down by the faithful during the lifetime of the Prophet, on bones, on palm leaves, on potsherds, and on whatever other materials were at hand, as well as being preserved in "the breasts of men."
But it was the third caliph, Uthman (644-61), who first charged a small group of men of Medina with codifying and standardizing the text.
Alarmed by reported divergences in the recitation of the revelation, he commissioned one of the Prophet's former secretaries, Zayd b. Thabit, and several prominent members of Quraysh - Abd Allah b. al-Zubayr, Sa‘id b. al-‘As, and Abd al-Rahman b. al-Harith are those most often mentioned - to produce a standard copy of the text, based on the compilation in the keeping of Hafsah, daughter of Umar.
If there was disagreement over language among members of the commission, it was to be resolved in accordance with the dialect spoken by Quraysh.
Once the standard text had been established, several copies were made and sent to major cities in the Islamic domain, specifically Damascus, Basra, Kufa, and perhaps others.
Although there are variations in detail, for example, in the list of names of those who served on Uthman's commission and in the list of cities to which copies were sent, this basic outline is not in dispute within the Muslim world.
Oral recitation nevertheless remained the preferred mode of transmission, and, as time passed, variant versions of the text proliferated - the kind of organic change that is endemic to an oral tradition.
In addition, because of the nature of the early Arabic script, in which short vowels were not indicated and consonants of similar form were only sometimes distinguished by pointing, writing, too, was subject to misunderstanding, copyist's error, and change over time.
In the early tenth century, at Baghdad, Abu Bakr Ibn Mujahid (d. 936) succeeded in reducing the number of acceptable readings to the seven that were predominant in the main Muslim centers of the time: Medina, Mecca, Damascus, Basra, and Kufa.
Some Qur'an readers who persisted in deviating from these seven readings were subjected to draconian punishments.
Nevertheless, with the passage of time, additional variant readings were readmitted, first "the three after the seven," then "the four after the ten."
The modern Cairo edition, prepared at al-Azhar in the 1920s, is based on one of the seven readings permitted by Ibn Mujahid, that of Abu Bakr ‘Âsim (d. 745) as transmitted by Hafs b. Sulayman (d. 796).
What is important to retain from her article is that the Cairo edition is based, at a minimum, on a second-hand verbal transmission. It is possible that Mary's apparent demotion in Allah's book of unchanging truths was simply an error in communication, oral transmissions being notoriously unreliable? Yes, but not so unreliable as to make a mistake of this magnitude.
Could some powerful men, e.g., caliphs, in their arrogance and to further their own agenda, do like God who, His Book of immutable facts admits to changing His mind, and removed the verse about Mary being a messenger of Allah in one of the later editions of the Koran?
Her demotion had to be deliberate and may have had something to do with the sayings of Muhammad which were collected more than one hundred years after his passing in which he makes his views about women abundantly and depressingly clear.
They could, of course, demote her, but not dismiss her completely, the greatest needing a lesser messenger in the person of her son to attest to his pre-eminence among Allah's better known spokespersons.