But I have trusted in Your mercy; my heart shall rejoice in Your salvation. I will sing to the LORD, because He has dealt bountifully with me.
Psalm 13 is a psalm of lament that begins with the cry “how long” repeated four times in verses 1 and 2. David felt abandoned and alone.
But verses 5 and 6 mark the turning point, where David’s faith in God’s mercy takes over and he remembers God’s previous blessings and His sure promises.
“What a surprising change is here in a few lines! In the beginning of the psalm we have him drooping, trembling, and ready to sink into melancholy and despair; but, in the close of it, rejoicing in God, and elevated and enlarged in his praises. See the power of faith, the power of prayer, and how good it is to draw near to God” (Matthew Henry’s Commentary).
Discover more about God’s mercy and His promises in the article “God's Promises.”