4 Because they have seen, then, “Make a joyful noise unto the Lord, all you lands”. You already know what it is to make a joyful noise. Rejoice, and speak. If you cannot express your joy, shout ye; let the shout manifest your joy, if your speech cannot: yet let not joy be mute; let not your heart be silent respecting its God, let it not be mute concerning His gifts. If you speak to yourself, unto yourself are you healed; if His right hand has healed you for Him, speak thou unto Him for whom you have been healed. “Sing, rejoice, and make melody.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)