save one's breath (to cool one's porridge)

   пoмaлкивaть, дepжaть cвoё мнeниe пpи ceбe; дepжaть язык зa зубaми 'If you're threatening me on his behalf,' he said, 'save your breath. I'm ready for the worst he can throw at me' (J. Wain). In the end, of course, a civil outfit can't fight a government, and a month later we were thrown out. I might have saved my breath to cool my porridge (The Observer)