This is a family song, a song to be sung by the people of God, the family of those who love their Father-God. It's a song about His awesome creation and about His faithfulness among the peoples of the earth. It's a song of praise, a song sung by those who know Him and are glad to be reminded of Him and of His works as they come early in the morning to the temple on Mount Zion.
At its beginning, the people turn to one another and sing, "Rejoice in the Lord, O you righteous! For praise from the upright is beautiful." They also exhort those with instruments to play well for God in response to their praise.
Then, in the next two verses, they turn and sing high praise directly to the Lord Himself. They do it simply by expressing all their experience of Him, all they know and love about the God of Israel. They sing, "For the word of the Lord is right, and all His work is done in truth. He loves righteousness and justice; the earth is full of the goodness of the Lord!"
They sing of a God Who made everything there is by His mere word, and of a God before Whom all peoples should stand in awe, since He is their mighty Creator. He's a God before Whom the plans made by even the mightiest nations are as nothing, but a God Whose own plans stand forever. And at the same time He's such a God that all Who love Him are truly blessed.
In fact, He is so great that He knows every heart and every action of every person in the world. No one can succeed in this world by means of great armies, great strength, or mighty weapons, but instead "the eye of the Lord is on those who fear Him" - on those who recognize that He's LORD of all - and on those who hope in His mercy. He will deliver them in every situation.
Finally, in the last stanza, the family of those who love and fear Jehovah all join together to declare their faith and love. Together they sing, "Our soul waits for the Lord; He is our help and our shield. For our heart shall rejoice in Him, because we have trusted in His holy Name." Finally, they all sing the family prayer. Joyfully, they sing, "Let Your mercy, O Lord, be upon us, just as we hope in You!"
Are you part of that family? Do you sometimes just rejoice to stand with the other people of God to praise Him? Do you rejoice to be reminded of His sovereignty and faithfulness?