5 Guard the mouth of your heart from evil, and you will be innocent: the tongue of your body will be innocent, your hands will be innocent; even your feet will be innocent, your eyes, your ears, will be innocent; all your members will serve under righteousness, because a righteous commander has your heart. “Then shall they say among the heathen, the Lord has done great things for them.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)