I believe I’ve read somewhere in scripture that Muslims will fight Muslims but I can not remember where? Do you recall the prophecy? Will they defeat each other? Could that be how Psalm 83 is fulfilled?
The Angel of the Lord told Hagar that Ishmael would be a wild ass of a man who would live in hostility toward all his brothers (Genesis 16:11-12). Since the Bible does not mention any brothers of Ishmael except Isaac, scholars often apply this to the descendants of Ishmael as well.
The Bible doesn’t tell us exactly how Psalm 83 will be won, but the Lord has been known to turn His enemies against each other. Judges 7:22 and Ezekiel 38:21 are two examples