வாயைத் திறந்தால் வம்பு
Vaayai thirandhaal vambu
Meaning
Speak without thinking, and you invite trouble - words are best measured before they leave your mouth.
Story
At a gathering, someone thoughtlessly revealed a friend's secret. That single sentence broke a friendship of many years between two families. He realized - far too late - exactly why elders warned that loose talk invites trouble.
Reader's Note
Thinking twice before speaking always beats regretting it afterward.