Who put zabar and zer on Quran?

The zabar (fatha) and zer (kasra) are diacritical marks used in Arabic script to indicate vowel sounds and are part of the system developed by the 7th-century scholar Abu al-Aswad al-Du'ali. He introduced these marks to aid in the correct pronunciation of the Quran, ensuring accurate recitation and comprehension of the text. This system was further refined by later scholars, but al-Du'ali is credited with laying the foundational groundwork for Arabic diacritics.