The prayer of Psalm 19:14, and indeed all of our prayers, are addressed to a God who is described here as a "Rock."  He is not some wimpy, wavering deity who can be shaken by circumstances; He is Rock solid and unimaginably strong.  And notice what the verse says.  He is not just any ol' rock; he is your Rock.  He is the source of your strength.  He is the firm place for you to stand.  He is the fortress where you can find protection.  God is your Rock.