The grammarian Abū al-Fatḥ 'Ubayd Allāh ibn Aḥmad collected several of the various manuscripts and produced a corrected copy which ibn Duraid read and approved. Originally in three manuscript volumes, the third largely comprised an extensive index.[2] Published in Hyderabad, India in four volumes (1926, 1930).[26] The historian Al-Masudi praised Ibn Duraid as the intellectual heir of Al-Khalil ibn Ahmad al-Farahidi, the compiler of the first Arabic dictionary, the Kitab al-'Ayn (كتاب العين), i.e. "The Source Book".[27] in his Kitāb al-Fihrist Al-Nadīm reports a written account by Abū al-Fatḥ ibn al-Naḥwī that Ibn Duraid examined the manuscript of Kitāb al-'Ayn at Baṣrah in 248H/ 862CE.[5] Al-Nadim also names ibn Duraid among a group of scholar proofreaders who corrected the Kitāb al-'Ayn.[11] However while Ibn Duraid's dictionary builds on al-Farahidi's - indeed Niftawayh, a contemporary of Ibn Duraid's, even accused him of plagiarizing from al-Farahidi[28][29] - Ibn Duraid departs from the system which had been followed previously, of a phonetic progression of letter production that began with the 'deepest' letter, the glottal pharyngeal letter "ع" (عين), i.e. ʿayn meaning "source".