Thus, the founders of grammar were Sîbawayh and, after him, al-Fârisî and Az-Zajjâj. All of them were of non-Arab (Persian) descent. They were brough… - Ibn Khaldun

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Thus, the founders of grammar were Sîbawayh and, after him, al-Fârisî and Az-Zajjâj. All of them were of non-Arab (Persian) descent. They were brought up in the Arabic language and acquired the knowledge of it through their upbringing and through contact with Arabs. They invented the rules of (grammar) and made it into a discipline (in its own right) for later (generations to use). Most of the ḥadîth scholars who preserved traditions for the Muslims also were Persians, or Persian in language and upbringing, because the discipline was widely cultivated in the 'Irâq and the regions beyond. Furthermore all the scholars who worked in the science of the principles of jurisprudence were Persians. The same applies to speculative theologians and to most Qur'ân commentators. Only the Persians engaged in the task of preserving knowledge and writing systematic scholarly works. Thus, the truth of the following statement by the Prophet becomes apparent: 'If scholarship hung suspended in the highest parts of heaven, the Persians would attain it.'