From Multi Theft Auto: Wiki

Wrong hijri months order it should be like this: --Walid (talk)

Note: i don't know why the wiki page change the order (maybe because it's arabic language) just copy and paste the code in your text editor (notpad++), you can go here to change a page language: Special:PageLanguage.

local hijriMonths = {"محرم","صفر","ربيع الأول","ربيع الثّاني", "جمادى الأولى","جمادي الثاني", "رجب","شعبان","رمضان","شوال","ذو القعدة","ذو الحجة"}

function getHijriMonth()
    local time = getRealTime()
    local month = time.month + 1
    return hijriMonths[month]

Also try to change the function name to getHijriMonth.