Psalms 13:5,6

‘But I have trusted in your covenant love (lovingkindness within the covenant);

My heart will rejoice in your salvation.

I will sing to YHWH,

Because he has dealt bountifully with me.

But the psalmist finishes on a note of assurance. In the darkness he finds light. He reminds YHWH that he is trusting to His covenant love. That is what the covenant is all about, that YHWH will act on behalf of those who are faithful towards Him. So he anticipates deliverance, and that he will again sing to YHWH, because he expects Him to deal bountifully towards him, indeed know that He must do so for He has chosen him as His own. For he who believes in God must believe that He is, and that He is a rewarder of those who diligently seek Him (Hebrews 11:6). So in the end his despair vanishes in the renewed faith that his prayer has revived.