שומר פיו ולשונו שומר מצרות נפשו
משלי
If you guard your mouth you save yourself a lot of trouble.
A true story [with some details changed]:
An older boy who had a LOT of trouble in shidduchim FINALLY FINALLY found a young lady who ALSO had been on the long frustrating world of shidduchim with no success and they decided to get engaged. He was from Israel and her family from chutz la'aretz, so her family flew in for the engagement party. Everything was ready to go but on the DAY of the party the shadcham called the father of the boy to tell him that the girl's side said it's OFF and they were furious and left in a huff back to chutz la'aretz. The father was understandably shocked and requested an explanation which was not forthcoming. The shadchan just said that they were angry at me for what I did and left the country.
The father of the erstwhile chosson was so distrught that he suffered a HEART ATTACK! His Rov came to visit him and he related the whole story. The Rov then got in touch with the girl's family's Rov in chutz la'aretz who told him the whole story.
It turns out that the girl's aunt had been in a pharmacy and saw that the boy had purchased medication for mental illness and quickly reported back to her family the shocking news. They thought they had been duped and this crucial information had been concealed so they called the whole thing off and returned home.
The TRUTH was that the boy had actually bought medication against SPRING ALLERGIES from which 40 percent of the population suffers. The aunt simply mixed up because the name of the medication was similar to the name of medication for mental illness but in fact it served a COMPLETELY different purpose.
All explanations to the girl's family that a terrible mistake had been made fell on deaf ears and so the young man and young woman remained single.
MORAL OF THE STORY: Ask a shyla before you talk!!!:-)
Of course this was the will of Hashem and הכל בידי שמים but we still must be CAREFUL before we talk.