Final answer:
In Greek mythology, Tereus assaulted his wife's sister, Philomela, and cut out her tongue to silence her, but this is not explicitly represented in the provided texts.
Step-by-step explanation:
The information provided touches on various mythological and literary sources, making it somewhat challenging to pinpoint exactly which figure "Tereus" the question is about.
However, in Greek mythology, Tereus was a king of Thrace who committed a grave injustice against his wife's sister, Philomela. He deceived Philomela, lured her away under false pretenses, assaulted her, and then cut out her tongue to prevent her from speaking about the crime.
If this is the account the question refers to, it's important to handle the explanation and discussion of such disturbing subject matter with sensitivity and an understanding of the context in which the myth was created and has been traditionally interpreted.