hold your tongue

US /hoʊld jʊər tʌŋ/
UK /hoʊld jʊər tʌŋ/
"hold your tongue" picture
1.

to remain silent and not speak, especially when you want to say something negative or critical

:
I had to hold my tongue when my boss made that ridiculous suggestion.
It's best to hold your tongue if you don't have anything nice to say.