Truth is concurrence between thought, word and deed. It must be true
to fact and at the same time pleasant. If by speaking the truth,
another is hurt it ceases to be truth and becomes himsa [harming].
There is a story which illustrates this point.
In olden days there was a sage renowned for his austerities and
observance of the vow of truth. It so happened that once when he was
sitting by his little hut, a frightened man with a bundle ran past
him and disappeared into a cave nearby. A couple of minutes later
there came a band of fierce robbers with gleaming knives, apparently
looking for this man. Knowing that the sage would not lie, they asked
him where the man with the bundle was hiding. At once, the sage, true
to his vow of not uttering falsehood, showed them the cave. The cruel
robbers rushed into it, dragged out the scared man, killed him
mercilessly and departed with his bundle. The sage never realised God
in spite of his austerities and tenacity for truth for he had been
instrumental in the murder of a man. This is not the kind of truth
that yoga requires. It would have been better if the sage had
remained quiet for that would have saved the poor man. Great care is
therefore to be exercised in speaking and each word must be carefully
weighed before it is uttered.