don't say, won't say
言わぬに越したことはない。
It's best not to say anything.
物言わぬ友達は今朝死んだ。
My silent friend died this morning.
言わぬと斬るぞ
Tell me, or I'll cut you down.
— Sanjuro (1962)
言わぬか!
Speak up!
— 羅生門 (1950)