This story comes in Mahaabhaarat in reference to Draupadee's question asked from the knowers of Dharm sitting in the Dice court. Vidur Jee told this story of Sudhanvaa in this regard to the kings sitting in the assembly.

He said - "There was a Daitya King named Prahlaad (the son of Daitya Hiranyakshyap). He had a son named Virochan. Once Virochan entered into quarrel with the son of Maharshi Angiraa, Sudhnavaa, for a bride, that "I am superior, I am superior". After a brief quarrel both decided to settle their case in Prahlaad's court, so they both went to his court. They presented their case to him and asked them to tell them the truth that who was superior between them. Hearing the subject of their quarrel, Prahlaad got scared. Seeing his condition Sudhanvaa filled with rage and said - "If you will not tell the truth or will not answer at all, your head will split into 100 pieces by Indra's Vajra." Hearing this Prahlaad started trembling. He himself could not decide anything, so he went to Kashyap Jee. He said to Kashyap Jee - "You know everything, please guide me."

Kashyap Jee said - "He who knows everything and does not speak and does not answer, because of temptation, or anger, or fear becomes the prey of thousand nooses of Varun. And the person who cited as the witness, with regard to some knowledge, speaks carelessly, becomes the cause of thousand nooses of Varun for his own people. Only one noose is loosened after a full one year. Therefore that he knows should always speak without hiding anything. In any assembly, if a person is worth rebuked is not rebuked, its half the sin goes to the assembly head, its one-forth sin goes to the person who is to be rebuked, and the remaining one-fourth sin goes to those people who are present there. On the other hand, in an assembly if the person who is to be rebuked, is rebuked, the head of the assembly gets free from all sins and the other members also are not attached to it. It is only the person who is to be rebuked is fully responsible for it. O Prahlaad, If somebody asks the knower of the morality a question about morality, and if he answers incorrectly, he destroys the Punya (merits) of his seven generation up and seven generation down.

The grief of the following people are of the same degree - (1) a person who has lost all his wealth, (2) a woman who has lost her son, (3) one who is in debt, (4) one who is separated from his companions, (5) a woman who has lost her husband, (6) one who has lost everything because of the King, (7) a woman who cannot bear children, (8) who has been devoured by tiger, (9) one who is a co-wife, and (10) the one who has lost his all property because of false witness. These grieves are those for who tell lie. [when a person becomes a witness?] A person becomes a witness if he seas, listens or understand something, therefore a witness should always speak truth."

Prahlaad Jee came back to his court and said - "O Virochan, Sudhanvaa is superior is to you. as his father Angiraa is superior to me. That is why Sudhanvaa is the master of your life." Sudhanvaa got very happy and satisfied to hear thhis, he said - "Since you have spoken the truth in spite of losing your son, I grant him 100 years."

REFLECTION
This When one knows something, he should speak truth. Who tells a lie he is a liar, but even who does not speak at all he also comes in the category of liars. Means when one keeps silence in spite of knowing everything, he encourages the sins and crimes.