Shaykhul Islaam Ahmad ibn Taymeeyah 728AH (May Allah have mercy on him) said,

اللسان العربي شعار الاسلام و أهله, و اللغات من أعظم شعائر الأمم التي بها يتميزون

“The Arabic tongue is the symbol of Islaam and its people, and languages are of the most significant signs by which nations are distinguished.”

Source: Iqtidaa as-Siraat al-Mustaqeem 1/462