As for (the ruling of) learning a language other than the Arabic language then it is not prohibited. Rather, it may even be compulsory if it is the only means in calling a non-Arabic speaker to Islam – meaning we are unable to call him to Islam unless we learn his language in order to be able to communicate with him.
So in this case, learning the language of that individual becomes fard kifāyah (an obligation which if it is carried out by some people then the obligation is removed for the rest of the community). It is a must that we inform those non-Arabs about the religion of Allāh and how can we do this except by speaking to them in their language.
Allāh the All Mighty says;
۞ وَمَا أَرْسَلْنَا مِن رَّسُولٍ إِلَّا بِلِسَانِ قَوْمِهِ لِيُبَيِّنَ لَهُمْ ۞
“And we sent not a Messenger except with the language of his people, in order that he might make (the Message) clear for them” [Sūrah Ibrāhīm 14: 4]
Therefore, sometimes learning a foreign language may be obligatory if the only way you can give daʿwah to the people is by learning their language.
However, what I disapprove and view to be hazardous is teaching our young children at the age of 5 or 4, the English language so that it becomes their first language, this is what I object to. If there is a need to learn a language other than Arabic in order to call the people (to Islam) then it becomes fard kifāyah and this is also the case if there is a need to learn any of the permissible worldly affairs.
It had been authentically reported that the Prophet ﷺ ordered Zaid bin Thābit to learn the language of the Jews, which is Hebrew and not Arabic. This was because the Prophet ﷺ used to correspond with the Jews and he needed to learn their language in order to be able to read what they sent him and likewise to write to them. Shaykh al-Islam Ibn Taymīyyah mentioned that Zaid Bin Thābit managed to learn Hebrew in 16 days – I wonder how long would it take Adam to learn English? Shaykh al-Islam Ibn Taymīyyah stated that Zaid managed to learn the Hebrew language in such a short space of time because of its similarities to Arabic and this is true, since the early Arabs were far better than us in terms of intelligence and their strength of memory. One poet (at that time) would come and recite a poem consisting of 100 lines and the people (the listeners) would have memorized it by the time he departed. As for our time now, then if I were to recite 1 line of poetry to students who attend for the purpose of learning, how many do you think would memorise it? Maybe one would memorise it or even maybe no one would.
Nevertheless, I say that I object and view that we are in dangerous grounds when teaching our young children the English language, since it may become their main language. It is also feared for the child that if he learns English, he would not suffice with just speaking it, rather he may try to read books. He will pick up English books and read English literature or any other type of literature – depending on the language he speaks, and great harm will take place. So the matter is not only subject to learning to speak a language but rather the person may desire to read the books written in this particular language in order to practice reading and pronunciation of the language and we do not know what (evils) are in those books. It has been mentioned that the books which are designed for the purpose of teaching English contain some evils.
 The Shaykh is referring to someone present at the gathering.
 [TN]: Shaykh Muḥammad ibn Ṣāliḥ al-ʿUthaymīn mentioned in his Majmūʿ – Book of knowledge, without a doubt, it may sometimes be obligatory when it is pertaining to Daʿwah sometimes. I did not learn it and I wish that I had learned it. Sometimes I had to make use of a translator who could not fully express what I intended to say. I will mention a story that occurred between me and some men from the Islamic Awareness Establishment in the Masjid of Jeddah airport. After Fajr prayer we were speaking about the deviancy of the Tijānī sect and how it has left the realms of Islam and so on. I began to speak what I knew about them until a man approached, seeking permission to translate my speech, so I granted him permission. Then another man come and said that the translator was praising the Tijānī sect. I was amazed and said, “Indeed to Allāh we belong and truly, to Him we shall return.” If I had known this language then I would not have been in need of these tricksters.