Dunno I'm sceptical, something doesn't sit right with it. It does look in very good condition and the writing doesn't look quite right in terms of the script form used at the time. Why wouldn't it be more well known if it is indeed Mo's letters? Doesn't make sense, I've certainly never heard of them being still in existence.
I spent a year studing the process of transference of Islamic texts (Qu'ran, hadith etc...) from the time of Mo 'till now. I've forgotten alot of it, and wish I had my old text-books to be able to give references/info etc...
To me it seems just by looking at the different letters presented, that the type of scripts used look to be from later periods than at the time of Mo, and different periods of time to each other. Some have older script form, and some have later script form.
Just from squizzing through wiki, there's this:
PERF 558 is the oldest surviving Arabic papyrus, and the oldest dated Arabic text from the Islamic era, dating from 22 AH (AD 642) and found in Heracleopolis in Egypt. It is a bilingual Arabic-Greek fragment, consisting of a tax receipt, or as it puts it "Document concerning the delivery of sheep to the Magarites and other people who arrived, as a down-payment of the taxes of the first indiction." Features of interest include:
The first well-attested use of the disambiguating dots that would become an essential feature of the Arabic alphabet;
It begins with the Islamic formula "Bismillah ir-rahman ir-rahim" (In the Name of God, the Merciful, the Compassionate)
It records the date both in the Islamic calendar (Jumada I, year 22) and in the Coptic calendar (30 Pharmouthi, 1st indiction), allowing confirmation of the traditional date of the Hijra.
In Greek, it calls the Arabs "Magaritae", a term, believed to be related to the Arabic "muhajir", emigrant, often used in the earliest non-Islamic sources. It also calls them "Saracens".
After excavation, the papyrus was put in the Erzherzog Rainer Papyrus Collection in Vienna.
Dots and hamzas added; otherwise, spelling uncorrected.
بسم الله الرحمن الرحيم هذا ما اخذ عبد اله
ابن جبر واصحبه من الجزر من اهنس
من خليفة تدراق ابن ابو قير الاصغر ومن خليفة اصطفر ابن ابو قير الاكبر خمسين شاة
من الجزر وخمس عشرة شاة اخرى اجزرها اصحاب سفنه وكتئبه وثقلاءه في
شهر جمدى الاولى من سنة اثنين وعشرين وكتبه ابن حديدو
In the name of Allah, the Compassionate, the Merciful. This is what `Abdallah,
Son of Jabir, and his companions-in-arms, have taken as of slaughter sheep at Heracleopolis (Ihnas)
from a representative of Theodorakios (Tidraq), second son of Apa Kyros (Abu Qir), and from a substitute of Christophoros (Istufur), eldest son of Apa Kyros (Abu Qir), fifty sheep
as of slaughter and fifteen other sheep. He gave them for slaughter for the crew of his vessels, as well as his cavalry and his breastplated infantry in
the month of Jumada I in the year twenty-two. Written by Ibn Hadidu.
P. Berol. 15002 - One Of The Earliest Arabic Parchments From 22 AH / 643 CE
22 AH / 643 CE.
P. Berol. 15002.
The translation of the document is given below.
.. and half ... in ...
[... in the] year twenty-two.
It is a parchment fragment of a receipt for the settlement of accounts. This is one of two earliest Arabic papyri; the other one being the celebrated PERF No. 558. Not much attention had been paid to this parchment because of its fragmentary nature.
Very much like PERF No. 558, P. Berol. 15002 also shows dotting. Dots can be seen on the letter ن.
The year 22 is the first Islamic year for which any dated documents written in Arabic survive, and there are only two of those: P Berol 15002, which is unfortunately fragmentary, and PERF 558, the first complete Arabic document of the Muslim era.http://www.islamic-awareness.org/History/Islam/Papyri/jones.html
Here is a list of links to some of the earliest Islamic period arabic papyri:
684 - 685 CE
This page has a list of dated muslim writings papyri/graffiti/coins etc... from 622 CE:
Here is a page with a list of early Qu'ranic inscriptions/writings from the year 650 CE:
Here is a page detailing in list form the various writings from 637 mentioning Mo: