It is certainly standard Arabic script, which is used for the quite different Urdu language of India and Farsi of Iran. Some letters may differ, as the French will use è Spanish ñ and Old Rnglish ð and æ. Urdu was the Indian Army language for most regiments, before there was a Pakistan.
I can read Arabic after a fashion, most of the time and in standard fonts, but I can see nothing intelligible here. Arabiuc letters have terminal forms and forms for use in the middle of a word, and I don't see any of the latter - which is quite meaningful if it is engraved, less so if it is done with letter stamps. It looks to e like a collection of letters and numbers, like you might get on modern military equipment.
Part of it could be TABA, unless the As, vertical strokes, are really just dividing lines. What look like the figure 2 turned on its side probably are the figure 2, giving the number 22, and the similar one like an upturned 3 would be a 3. If no other information, that suggests something institutional, rather than some tribesman's personal inscription.
Stastically, just on the numbers of men it could have been issued to, the odds are on its being Indian, and after that Egyptian. It isn't really true that Indian troops used Martini-Henrys very late, as a matter of keeping them under control. There are olenty of pictures of Indian regiments with Long Lee-Enfields, some before the day of the SMLE.