In the Markandeya Samasya Parva (Vana Parva), we have the very interesting story of the Rishi Kaushika learning dharma from the Vyaadha (hunter) and butcher, Dharmavyadha.

Dharmavyadha explains to Kaushika how Dharma is extremely nuanced and it must be understood correctly. The vedas say that speaking the truth (satya) is dharma BUT this is not always true.

When the truth can cause harm to someone or lead to death, satya becomes adharma. The Mahabharatha also has a story illustrating this point very clearly.

A brahmana named Kaushika had undertaken a vow of speaking nothing but the truth. As he sat meditating in his ashrama, a group of terrified traders ran in and seeing him, they begged shelter. “A group dacoits is after us,” they told him and they were desperately looking to hide. If the dacoits found them, they would be killed. The group quickly hid away inside the ashrama, relieved that they had found shelter.

A short while later, the dacoits burst in. They saw Kaushika and demanded to know if a group of traders had come that way. Kaushika thought of his vow to only speak the truth and he truthfully told the dacoits that the traders were hiding inside.The dacoits rushed in and killed the hidden group.

Kaushika had told the truth. He also followed his vow. But he went to Naraka because in that situation neither his vow nor the truth were important. Protecting innocent lives was Dharma and he had failed.