Psalm 40:1-3 King James Version (KJV)
40 I waited patiently for the Lord; and he inclined unto me, and heard my cry.
2 He brought me up also out of an horrible pit, out of the miry clay, and set my feet upon a rock, and established my goings.
3 And he hath put a new song in my mouth, even praise unto our God: many shall see it, and fear, and shall trust in the Lord.
David said, "God put a new song in his mouth, a song of praise to God." After all that he have been through, in every mistakes he made, in every failure he have been experienced and even in a very difficult times of uncertainty. Even after everything he had just been through…the miry bog, the destructive pit…He would praise God because he knew that God can always make our mess into a message of hope and salvation.