Which Truth should be revealed and which should be hidden? [duplicate]

Question

• As in Mahabharata Lord krishna asked Yudishtra to Lie as his guru's son Aswathama was dead although it was a elephant it was a Lie,and it was for dharma.
• Yudishtra was not so willing to lie as it is adharma but as the lord alknowing said in that situation lie is good as for dharma
  

QUESTION :

• Lord Krishna was a god and so he was confident in that situation but as a conditioned soul how can we choose the path of telling and hiding a truth.
  

EXAMPLE :

• A women who has a daughter to be married has wrong affair with other man should be revealed or not ?
• If not revealed she would not be punished and she will continue to do adharma.
• If we reveal it then the family name will be completely destroyed and her daughter's marriage will not occur as everyone thinks as a mother same as the daughter.

• Or it should be revealed after her marriage and if later revealed it will be also like hiding?

• There many situations that arise while telling a truth.

• Is there any definite scriptural way to tell and hide the truth in the world?

Answer 1

A women who has a daughter to be married has wrong affair with other man should be revealed or not ?

In this case, the father should reveal it. Not doing so is actually a punishable deed.

Manu Smriti 8.205. He who gives (a damsel in marriage), having first openly declared her blemishes, whether she be insane, or afflicted with leprosy, or have lost her virginity, is not liable to punishment.

EDIT:

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Is there any definite scriptural way to tell and hide the truth in the world?

Yes there are. Although speaking only truth and shunning falsehood is recommended for all people at all the times, but in some situations speaking falsehood is also allowed as per scriptures.

Here are a couple of relevant verses.

8.103. In (some) cases a man who, though knowing (the facts to be) different, gives such (false evidence) from a pious motive, does not lose heaven; such (evidence) they call the speech of the gods

8.104. Whenever the death of a Sudra, of a Vaisya, of a Kshatriya, or of a Brahmana would be (caused) by a declaration of the truth, a falsehood may be spoken; for such (falsehood) is preferable to the truth.

Manu Smriti verses.

But even for these people (who spoke falsely) some sort of penances are prescribed (in the subsequent Manu Smriti verses) in order to clear the guilt. So, even though speaking falsely is allowed under certain circumstances, some amount of guilt is still attached to the act.