> Christian monastery in Islamic Sinai if the timing of the article is correct

https://en.wikipedia.org/wiki/The_Ladder_of_Divine_Ascent

According to this article his writings pre-date the Islamic conquest (639).

Of course, there was also this: https://www.sinaimonastery.com/index.php/en/history/mohammed

And St Catherine's is a fortress in the middle of the desert so who knows what it's status was, it was an interesting time (beginning of Islamic conquests).

The palimpsest was made during that time, though.