禍從口出

Trouble issues from the mouth (idiom). A loose tongue may cause a lot of trouble.

to go out / to come out / to occur / to produce / to go beyond / to rise / to put forth / to happen / (used after a verb to indicate an outward direction or a positive result) / classifier for dramas, plays, operas etc

variant of 出[chu1] (classifier for plays or chapters of classical novels)

mouth / classifier for things with mouths (people, domestic animals, cannons, wells etc) / classifier for bites or mouthfuls

disaster / misfortune / calamity

from / through / via / to follow / to obey / to engage in (an activity) / never (in negative sentence) / (Taiwan pr. [zong4]) retainer / assistant / auxiliary / subordinate / related by common paternal grandfather or earlier ancestor

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