Hello Duane and All,
Just a few quick notes. When Mohamed suggested a 10th century date, I presume the underlying assumption was that it's 903 from the birth of Christ (i.e., something reasonably close to our AD era). There are problems with that: this is a manuscript on paper, and paper is hardly ever used in Sinai Christian Arabic manuscripts before the mid-10th century. Also, the AD era was not used at the time, and neither was the Melkite Incarnation era discussed by Samir. There are some instances of an Alexandrian Incarnation era that I discuss in my article "New Works of Theodore Abu Qurra", but it never appears in colophons. The hand also doesn't look like the 10th century to me. (There is a great study on early Christian Arabic hands by Miriam Hjälm: "A Paleographical Study of Early Christian Arabic Manuscripts".) All in all a 10th-century dating, especially if it be early 10th century, looks extremely unlikely to me.
The 12th century date comes from Kamil's catalogue. Apparently, Kamil didn't notice the colophon and dated the manuscript approximately based on paleographic considerations. The UCLA site simply reproduced the date from Kamil's catalogue.
It is in principle possible to have a mixed date, where the month is given according to one system and the year according to another. This doesn't happen a lot, but occasionally it does; however, it's usually the Hijri year that is given with the month (or the liturgical season) indicated using another system, not the other way round. Looking through my notes here are some examples:
Sinai ar. NF Perg. 9 is dated to Friday,
the fourth last day of November 354 AH [which would convert to Friday, 29 November 965 AD].
Berlin,
SBB Ms. or. oct. 1108 is dated to the
middle of the Great Lent 438 AH [which would convert to 1047 AD].
Sinai ar. 434 has two dates one of which is Saturday,
11 February 533 [AH] [which converts to 1139 AD].
Sinai ar. NF Paper 56 has the date of 15
Baramhāt 805 [AH] [which converts to 1403AD] – possibly this is the date when the
manuscript was consulted rather than copied.
So assuming "903" is to be understood according to another era, the Anno Martyrum is the only plausible solution. 903 AMart = 1186/7 AD. I'm not saying this is the correct date - I'm just looking at different possibilities.
In my view, 903 AH (=1497 AD) is still the likeliest scenario. I would consider a 10th-century date very unlikely. If the manuscript is demonstrably earlier than the 15th century, then perhaps 903 AMart = 1186/7 AD is the solution, which corresponds neatly to Kamil's approximate date.
It would be helpful if Mohamed could tell us more about the reasons for early dating.
Happy New Year, everyone!
Alexander