Truth constitutes the essence of the Vedas. Control over passions constitutes the essence of truth. And self-denial (refraining from the worldly enjoyments) forms the essence of selfcontrol. These attributes are always present in a virtuous conduct.
वेदस्योपनिषत् सत्यं सत्यस्योपनिषद् दमः। दमस्योपनिषत् त्यागः शिष्टाचारेषु नित्यदा॥