I learned today that Arabic is the official language in these countries: Algeria, Bahrain, Egypt, Iraq (with Kurdish language), Israel (with Hebrew language), Jordon, Kuwait, Lebanon, Libya, Oman, Qatar, Palestine, Saudi Arabia, Somalia, Sudan, Syria, Tunisia, Yemen.
Although not its official language, Arabic is the liturgical language used by Muslims in these countries: Afghanistan, Indonesia, Iran, Pakistan, Turkey. I think liturgical language means a language that is used for religious and arts purposes. I wonder why the source that I got this information from did not include Malaysia.