Shaykh-ul-Islaam ibn Taymiyyah رحمة الله عليه said:
" وأما اعتياد الخطاب بغير العربية التي هي شعار الإسلام ولغة القرآن حتى يصير ذلك عادة للمصر وأهله ولأهل الدار وللرجل مع صاحبه ولأهل السوق أو للأمراء أو لأهل الديوان أو لأهل الفقه فلا ريب أن هذا مكروه فإنه من التشبه بالأعاجم وهو مكروه كما تقدم .
ولهذا كان المسلمون المتقدمون لما سكنوا أرض الشام ومصر ولغة أهلهما رومية وارض العراق وخراسان ولغة أهلهما فارسية وأهل المغرب ولغة أهلها بربرية عودوا أهل هذه البلاد العربية حتى غلبت على أهل هذه الأمصار مسلمهم وكافرهم وهكذا كانت خراسان قديما ثم إنهم تساهلوا في أمر اللغة واعتادوا الخطاب بالفارسية حتى غلبت عليهم وصارت العربية مهجورة عند كثير منهم ولا ريب أن هذا مكروه .
وإنما الطريق الحسن اعتياد الخطاب بالعربية حتى يتلقنها الصغار في الدور والمكاتب فيظهر شعار الإسلام وأهله ويكون ذلك أسهل على أهل الإسلام في فقه معاني الكتاب والسنة وكلام السلف بخلاف من اعتاد لغة ثم أراد أن ينتقل إلى أخرى فإنه يصعب عليه
واعلم أن اعتياد اللغة يؤثر في العقل والخلق والدين تأثيرا قويا بينا ويؤثر أيضا في مشابهة صدر هذه الأمة من الصحابة والتابعين ومشابهتهم تزيد العقل والدين والخلق
وأيضا فإن نفس اللغة العربية من الدين ومعرفتها فرض واجب فإن فهم الكتاب والسنة فرض ولا يفهم إلا بفهم اللغة العربية وما لا يتم الواجب إلا به فهو واجب
ثم منها ما هو واجب على الأعيان ومنها ما هو واجب على الكفاية
وهذا معنى ما رواه أبو بكر بن أبي شيبة حدثنا عيسى بن يونس عن ثور عن عمر بن يزيد قال كتب عمر إلى أبي موسى الأشعري رضي الله عنه أما بعد فتفقهوا في السنة وتفقهوا في العربية وأعربوا القرآن فإنه عربي
وفي حديث آخر عن عمر رضي الله عنه أنه قال تعلموا العربية فإنها من دينكم وتعلموا الفرائض فإنها من دينكم
وهذا الذي أمر به عمر رضي الله عنه من فقه العربية وفقه الشريعة يجمع ما يحتاج إليه لأن الدين فيه فقه أقوال وأعمال ففقه العربية هو الطريق إلى فقه أقواله وفقه السنة هو الطريق إلى فقه أعماله .. " اقتضاء الصراط المستقيم 2/207
"As for getting used to speaking in other than Arabic - the language which is the Shi`aar (Salient Feature) of Islaam and its people, and the language of the Qur'aan - until doing so (speaking in non-Arabic) becomes the habit of a town and its people, and the households, and with a man with his wife, and the people of the marketplaces, and the leaders, or the (Islaamic) government representatives, or the people of Fiqh (i.e. the `Ulamaa), then there is no doubt that this is Makrooh, because it is Tashabbuh (resembling) with al-A`aajim, and that is Makrooh as we have mentioned earlier.
For this reason, the Muslims of old, when they settled in the lands of Shaam and Misr, and the languages of the inhabitants were Rome, and the lands of Iraq and Khuraasaan, and the language of its people was Farsi, and the people of al-Maghrib (North Africa), and the language of its people was Berber - they taught the people of these lands Arabic, so much so that Arabic became the dominant language of all these towns, both for the Muslims and the Kuffaar. This is how Khuraasaan was in the past. Thereafter, they became lax in the issue of language and became accustomed to speaking Farsi, until it overpowered them and Arabic was abandoned by most of them, and there is no doubt that this is Makrooh.
The correct way is that people become accustomed to speaking in Arabic so that the children learn it in the homes and in their schools, so that the language of Islaam and its people becomes supreme (once again), and so that it can be easier for the people of Islaam to understanding the meanings of the Qur'aan and the Sunnah, and the Kalaam (Speech) of the Salaf (Pious Predecessors), contary to those who have become accustomed to another language and now wish to change to a different one, because that is difficult upon them.
Know also that becoming accustomed to speaking a particular language has a very powerful and clear effect on the mind, character and Deen of the person. It also has the effect of making one resemble the earliest generations of this Ummah, from the Sahaabah and the Taabi`een. Resembling them increases the intellect, Deen and character of the person. Moreover, the Arabic language itself is part of Deen. Knowing it is an obligatory duty. This is because understanding the Qur'aan and the Sunnah is Fardh (obligatory), and they cannot be understood except by understanding the Arabic language. Whatever is required in order for a Waajib (compulsory) duty to be carried out, is Waajib (compulsory) itself.
Then, from it is that which is Waajib upon all people and from it is that which is Waajib only upon some.
This is the meaning of what was reported by Abu Bakr ibn Abi Shaybah, (who said) "`Eesaa ibn Yoonus narrated to us from Thawr, from `Umar ibn `Yazeed, who said, "`Umar wrote to Abu Moosaa al-Ash`ari رضي الله عنه (saying), "As for what follows: Acquire understanding of the Sunnah, and acquire understanding of Arabic, and learn the Qur'aan in Arabic, because it is Arabic.
In another narration from `Umar
رضي الله عنه it is mentioned that he said, "Learn Arabic for it is part of your Deen, and learn al-Faraa'idh for it is part of your Deen.
This which `Umar
رضي الله عنه commanded is from the understanding of Arabic and the understanding of the Sharee`ah; it gathers what the person needs Then, from it is that which is Waajib upon all people and from it is that which is Waajib only upon some.
This is the meaning of what was reported by Abu Bakr ibn Abi Shaybah, (who said) "`Eesaa ibn Yoonus narrated to us from Thawr, from `Umar ibn `Yazeed, who said, "`Umar wrote to Abu Moosaa al-Ash`ari رضي الله عنه (saying), "As for what follows: Acquire understanding of the Sunnah, and acquire understanding of Arabic, and learn the Qur'aan in Arabic, because it is Arabic.
In another narration from `Umar رضي الله عنه it is mentioned that he said, "Learn Arabic for it is part of your Deen, and learn al-Faraa'idh for it is part of your Deen.
This which `Umar رضي الله عنه commanded is from the understanding of Arabic and the understanding of the Sharee`ah; it gathers what the person needs, because in the Deen is the understanding of statements and actions, and understanding Arabic is the road towards understanding (those) statements. Understanding the Sunnah is the road towards understanding its actions." [Iqtidhaa as-Siraat al-Mustaqeem, 2/207]