Know that habitual use of a language leaves a clear and powerful imprint on the intellect, the character, and one’s religious state. It also helps a person resemble the first generations of this community—the Companions and the Followers—and such resemblance refines the mind, the faith, and the morals.
Furthermore, the Arabic language itself is part of the religion, and acquiring it is an obligatory duty. Understanding the Book and the Sunnah is mandatory, and that understanding cannot be attained without knowledge of Arabic; therefore, whatever is indispensable for fulfilling an obligation is itself obligatory.
Within this duty, certain aspects are individually obligatory, while others are a collective obligation.
This is the meaning of the report related by Abū Bakr ibn Abī Shaybah: ʿĪsā ibn Yūnus narrated from Thawr, from ʿUmar ibn Zayd, who said: “ʿUmar wrote to Abū Mūsā al-Ashʿarī, may Allah be pleased with him:
‘To proceed: Acquire deep understanding of the Sunnah, gain mastery of Arabic, and render the Qur’an in correct Arabic, for it is Arabic.’”
In another narration from ʿUmar, may Allah be pleased with him, he said: “Learn…"
(1) Manuscripts B, J, and D read: “the Book of Allah and the Sunnah.”
(2) ʿIsa ibn Yunus ibn Abi Ishaq al-Sabiʿi, originally from Kufa, later settled in Syria as a murabit (a frontier volunteer in the path of Allah). Ibn Hajar describes him as “reliable and trustworthy.” He belongs to the eighth generation; all six canonical collectors transmitted from him. He died in 191 AH. See Ibn Hajar, Taqrib al-Tahdhib 2:103, no. 933.
(3) The words “on the authority of Thawr” are absent from manuscript A. Thawr ibn Yazid al-Kilaʿi; his biography has already been cited—see the Index of Names.
(4) The printed edition and manuscript B read “ibn Yazid,” but the correct reading is what is adopted here. See al-Bukhari, al-Tarikh al-Kabir 6:157. Al-Bukhari and Ibn Abi Hatim state: “ʿUmar ibn Zayd said: ʿUmar, may Allah be pleased with him, wrote to Abu Musa,” a mursal report transmitted from him by Thawr ibn Yazid. I have not found further information on him beyond what is mentioned here. See al-Tarikh al-Kabir 6:157 and al-Jarh wa-l-Taʿdil 6:109.
(5) The phrase “so acquire deep understanding of the Sunnah” is missing from manuscripts J and D.
(6) From this point a folio is missing in manuscript B; its continuation will be indicated at p. 531.