 Abū Abd Allāh al-Rūdbāri interpreted this to mean that the study of oral language is above all the other sciences – "tafsir" (exegesis), "Ḥadīth" (tradition), "fiqh" (Law) – as it perfects and connects these to discourse.Tha‘lab, was invited but declined to take a commission by the vizier al-Qāsim to write a commentary on the book "Compendium of Speech" by Maḥbarah al-Nadīm, which the caliph Al-Mu‘taḍid had ordered.He offered instead to work on the Kitāb al-‘Ayn of al-Khalīl, and the commission went to Al-Zajjaj.