BH Many chasidim nowadays specifically don't speak Hebrew as a casual language; rather, some dialect of Yiddish.
A similar concept was in the days of the Gemara, where many people specifically spoke Aramaic and not Hebrew
Also in the times of the Rambam, it's known that the Rambam wrote the guide to the perplexed in Arabic, since it's what most people spoke casually, and not Hebrew
What is the source for this? Is it because Hebrew is too holy to use casually? Is it a documented minhag or halacha?
I recall reading something in Torah Ohr about elevating the 70 languages, on the verse "under his feet was a brick of sapphire", because bricks are made by man, as opposed to stones, which are made by heaven, which is the difference between the holy tongue and the 70 languages...
But I'm not sure if this is the main source or just a deeper meaning, so does anyone know what the official source is?
Edit: This is NOT a duplicate of "is it a mitzvah to speak loshon hakodesh", since that is asking for sources regarding if one should, this is asking if there's an inyan to specifically not