IIRC, a _sura_ (possibly not the correct transcription) is a chapter in the Koran. What is the actual form/meaning of the word? Does it have anything to do with "writing"? Is there any morphological process in Arabic that would suffix a /-t/ or t-like sound to the word? I ask because a question has arisen about Malay surat 'to write' and its cognates. It's reconstructed as original Proto Austronesian (and could well be, if it originally meant something else, like 'decorate'), though to my knowledge it's not attested in Oceania, but only in the western languages which have been in contact with Arab/Islamized Indian traders for a very long time. The western AN word for 'read' is borrowed < Indic; it seems likely to me that 'write' could also be a loan.