1 I could wish, brethren, that we were rather listening to our father: but even this is a good thing, to obey our father. Since therefore he who deigns to pray for us, has ordered us, I will speak unto you, beloved, what from the present Psalm Jesus Christ our common Lord shall deign to give us. Now the title of the Psalm is “David's Song of praise.” The “Song of praise” signifies both cheerfulness, in that it is a song; and devotion, for it is praise. For what ought a man to praise more than that which pleases him so, that it is impossible that it can displease him? In the praising of God therefore we praise with security. There he who praises is safe, where he fears not lest he be ashamed for the object of his praise. Let us therefore both praise and sing; that is, let us praise with cheerfulness and joy. But what we are about to praise, this Psalm in the following verses shows us.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)