सत्यमेव जयते नानृतं
सत्येन पन्था विततो देवयानः ।
येनाक्रमन्त्यृषयो ह्याप्तकामा
यत्र तत्सत्यस्य परमं निधानम् ॥
satyam eva jayate nānṛtaṁ
satyena panthā vitato devayānaḥ |
yenākramanty ṛṣayo hy āpta-kāmā
yatra tat satyasya paramaṁ nidhānam ||
(Muṇḍaka Upaniṣad: 3.1.6)
“Truth alone triumphs, and not falsity [i.e., those who adhere to truth triumph and not those who engage in falsity]. Through truth is spread out the path of devas by which the ṛṣis of fulfilled desire ascend to that [domain] where there exists the supreme treasure of truth [i.e., Brahman].”
Commentary
Why should one adhere to truth? (1) Only the truthful are successful and triumphant in life, and (2) only the truthful can realize Brahman (as the path to Brahman consists of being truthful). Why should one not engage in falsity (even when it appears to produce immediate material benefits)? (1) It creates psychological stress (fear, worry, guilt, etc.), (2) it is detrimental to relationships and society (and can in some cases result in formal punishment), and (3) it results in inevitable long-term negative consequences in the form of troublesome karma.