trouble comes out of the mouth (i.e. from a loose tongue)
祸从口出
misfortunes come from the mouth;a loose tongue is a source of evil
病从口入,~disease goes in by the mouth and disaster comes out of it
祸从口出出(生)huò cónɡ kǒu chū
指说话不慎会招致灾祸。out of the mouth comes evil, A really tongue is an evil. All one’s troubles were caused by his tongue.