Classical Arabic (4th-9th century) short vowels are /a/, /u/, and /i/, and long vowels are /a:/, /u:/, and /i:/.
New Persian (1000-1200 years old) short vowels are /æ/, /o/, and /e/, and long vowels are /ɒ:/, /u:/, and /i:/
Orthographically speaking, /æ/ in Persian is written like /a/ in Arabic, /o/ like /u/, and /e/ like /i/. The same goes for the long vowels; /ɒ:/ for /a:/, /u:/ for /u:/, and /i:/ for /i:/
In Arabic loanwords in Persian, like kitaab/ketaab (written exactly the same way in Arabic and Persian, even with diacritics), which is a loanword from Arabic, why is it pronounced as /ketɒ:b/ in Persian, when it would make more sense for it to be pronounced as /ki:tɒ:b/, since I would assume /i:/ is closer to /i/ than /e/? In other words, why was the Arabic /i/ transferred to Persian as /e/ instead of /i:/?
Similar changes also apply to other words borrowed from Arabic. Few examples:
- imtiħaan/emtehaan "test"
- istiʕmaar/esteʔmaar "conquest/occupation"
- sulħ/solh "peace"