The Bhagavad Gita (16.2) mentions truthfulness as an important divine quality. Sri Ramakrishna teaches that by adhering to truth one attains God, the Supreme Truth. Since his mind was always one with God, truthfulness permeated Sri Ramakrishna's thoughts, words, and actions. He lived a life of total surrender to the Divine Mother. He could offer everything to the Divine Mother except his devotion to truth. In his own words: "After my vision of the Divine Mother, I prayed to Her, taking a flower in my hands: 'Mother, here is Thy knowledge and here is Thy ignorance. Take them both, and give me only pure love. Here is Thy holiness and here is Thy unholiness. Take them both, Mother, and give me pure love. Here is Thy good and here is Thy evil. Take them both, Mother, and give me pure love. Here is Thy righteousness, and here is Thy unrighteousness. Take them both, Mother, and give me pure love.' I mentioned all these, but I could not say: 'Mother, here is Thy truth and here is Thy falsehood. Take them both.' I gave up everything at Her feet but could not bring myself to give up truth."
According to a Sanskrit verse on truthfulness, the practice of truth has four aspects: speaking the truth; speaking what is pleasant; not speaking an unpleasant truth; and not speaking an untruth to please others.
Truthfulness is among the ethical disciplines described in Patanjali's Yoga Sutras as great vows. (2.30-31) Vyasa's commentary on sutra 2.30 reveals several facets of truthfulness: (1) Truthfulness is the correspondence of speech and mind to facts based on what is seen, heard, or inferred. (2) Spoken words can be considered truthful only if the hearer does not find them deceitful, delusive, or meaningless. (3) Words uttered to hurt others will amount to sin; though apparently truthful, such words only lead one to painful consequences. (4) Therefore, only truthful words beneficial to all creatures should be uttered after careful consideration.
Cautioning about the evil consequences of falsehood, Swami Vivekananda says: "To tell a lie, or cause another to tell one, or to approve of another's doing so─it is all equally sinful. A very mild lie is still a lie. Every vicious thought will rebound, every thought of hatred which you may have cherished, even in a cave, is stored up, and will one day come back to you with tremendous power in the form of some misery here."
The Mundaka Upanishad (3.1.6) declares that truthfulness leads to God-realization: "Truth alone prevails, not falsehood. By truth the path is laid out, the Way of the Gods, on which the seers, whose every desire is satisfied, proceed to the highest Abode of the True."
Swami Vijnanananda teaches: "God is Truth, and to realize Him you have to be completely truthful in your words and deeds. Hold fast to the way of truth, do harm to no one and God will draw you to His sheltering care. Truth must be adhered to very strictly. There should be complete harmony between preaching and practice. What comes out of your lips has to be acted upon."
In the words of Swami Premananda: "You will never lose if you adhere to truth. Hold fast to truth, and divine grace will flow to you through all channels. You will prosper not only in worldly affairs, but in spirituality as well. If you have truthfulness, every other virtue is sure to come in its wake."