In spite of God"s lack of response, David continued to trust in the Lord"s loyal love. He was confident that Yahweh would eventually deliver him and that he would rejoice in the Lord and sing praises to Him. The basis of this confidence was God"s bountiful goodness to him in the past. The goodness of God is a recurring theme in the psalms. [source][source][source]
"The actual song of praise would burst forth once deliverance had been accomplished, but the knowledge that deliverance was coming created an anticipatory calm and sense of confidence." [1][source]
"The three pairs of verses climb up from the depths to a fine vantage-point of confidence and hope. If the path is prayer (3f.), the sustaining energy is the faith expressed in Psalm 13:5. The prospect from the summit (5) is exhilarating, and the retrospect (6) overwhelming." [2][source]
When the heavens seem to be brass and we feel God has departed from us, we should continue to trust Him and wait for His salvation. We can find encouragement by remembering His past loyal love and goodness to us. [3][source]