Mbh 12.109.2a

"'Bhishma said, "To tell the truth is consistent with righteousness. There is nothing higher than truth. I shall now, O Bharata, say unto thee that which is not generally known to men. There where falsehood would assume the aspect of truth, truth should not be said. There, again, where truth would assume the aspect of falsehood, even falsehood should be said. That ignorant person incurs sin who says truth which is dissociated from righteousness. That person is said to be conversant with duties who can distinguish truth from falsehood.[334] Even a person that is disrespectable, that is of uncleansed soul, and that is very cruel, may succeed in earning great merit as the hunter Valaka by slaying the blind beast (that threatened to destroy all creatures).[335] How extraordinary it is that a person of foolish understanding, though desirous of acquiring merit (by austere penances) still committed a sinful act![336] An owl again, on the banks of the Ganges, (by doing an unrighteous deed) obtained great merit.[337] The question thou hast asked me is a difficult one, since it is difficult to say what righteousness is. It is not easy to indicate it. No one in discoursing upon righteousness, can indicate it accurately. Righteousness was declared (by Brahman) for the advancement and growth of all creatures. Therefore, that which leads to advancement and growth is righteousness. Righteousness was declared for restraining creatures from injuring one another. Therefore, that is Righteousness which prevents injury to creatures. Righteousness (Dharma) is so called because it upholds all creatures. In fact, all creatures are upheld by righteousness. Therefore, that is righteousness which is capable of upholding all creatures. Some say that righteousness consists in what has been inculcated in the Srutis. Others do not agree to this. I would not censure them that say so. Everything, again, has not been laid down in the Srutis.