I remember there was a book which I read in childhood, it contained small small stories with different moral. One of the stories was, Zubaan ka Ras...where a person who is passing by a new town feels hungry and he knocks a door, door is opened by an old lady. Man asks for food from the lady, and lady starts preparing food for this stranger..while she is preparing batter for the roties, this man starts asking questions, one being " Lady your door is so narrow, if your cow dies, how will you take the cow out of your door?" quite angry with this question lady throws the batter at man's face. Some passer by sees the liquid dripping on man's face, and asks anqiously "what is this?", to which this man says "zubaan ka ras". Moral that was told in the story was that be wise in your speech.
Although this story was heard in childhood years, but I think this is ageless learning as here lies the start of self improvement. If man takes a pause and starts analysing what he is speaking, or asking, he will be astonished to see how comforting or breaking his words are. Path to self improvement is definately long, but one who has conquered his words, he has made a start. Speech is not the final criterian to prove one's level of wisdom but definately is a milestone. If its said, that one who doesnt think wrong will not say wrong...it also seems true that one who wants to think right, should start saying right.
