Hard to imagine today, but the grandmasters of Arabic grammar were superstars during their lifetime. Here is a list of the TOP 5 Arabic grammarians of all time.
The correct vowel endings damma, kasra, fatha in Arabic can be a headache. If you are careless, you could turn verse 9:3 of the Qur'an into blasphemy (kufr).
Arabic used to be written without dots in ancient times. At least it did, a long time ago. Could you read such sentences?