ㄅㄧㄥˋㄘㄨㄥˊㄎㄡˇㄖㄨˋbìngcóngkǒurùㄏㄨㄛˋㄘㄨㄥˊㄎㄡˇㄔㄨhuòcóngkǒuchū

病从口入,祸从口出
  1. 疾病往往入口飲食不慎引起災禍總是出口的話失當導致 前輩病從口入,禍從口出」,資歷儘量」。

Illness enters by the mouth, trouble comes out by the mouth (idiom)​. A loose tongue may cause a lot of trouble.