I read it in a book series about learning the German sign language. This one if it’s any help. But I can’t find any sources online accept Fuck that I found it:

The church barred deaf people from Holy Communion because they could not confess aloud. Deaf people were also prohibited from inheriting their family’s wealth […]

Oralism provided members of the privileged classes with deaf children a way to channel their children’s education and an opportunity to keep them away from the deaf community. Speaking has been associated with the higher classes and higher intellect, and the perception of signing has been the opposite.

US Bonus:

Bell also believed that sign language was an instrument of imprisonment and that its use prevented the “gesturer” from being a “true American”.

https://en.wikipedia.org/wiki/Oralism

The entire article is infuriating.