People trust many things, but David was trusting God’s love. Psalm 13:5a But I trust in your unfailing love. The word used for love here is the Hebrew word hesed. There is no English equivalent, and often translators use blended words to give a better understanding. These combinations are loyal love, steadfast love, faithful love, unfailing love, and loving kindness. Numerous scholars feel “loving kindness” represents hesed best.
“Many biblical words such as mercy, compassion, love, grace, and faithfulness relate to the Hebrew word hesed (חֶסֶד), but none of these completely summarize the concept. Hesed is not merely an emotion or feeling but involves action on behalf of someone in need. Hesed describes a sense of love and loyalty that inspires merciful and compassionate behavior toward another person.”
Unfailing Love Leads to Joy
Despite the enemy’s upper hand, despair, and the feeling that God was ignoring him, David trusted God’s unfailing love. By definition, this is the kind of love that acts, and God has not failed to act before. David trusted the compassion of God to bring him relief. This trust is so great that David anticipates joy will come. Psalm 13:5b I will rejoice because you have rescued me.
David can speak of the rescue in the past tense even though it has not happened. I believe David thought God was already at work to rescue him even though he couldn’t see it. Is David planning a victory party to give glory to God? We don’t know, but we can see the depth of his faith in verse five.
Moving from Despair to Joy
Psalm 13 shows that despair and joy can co-exist. David struggled in life, but as he trusted God, he could move to joy. As we live our lives, sooner or later, there will be a struggle, disappointment, or grief. Yet as we refocus on Jesus and His amazing love instead of only our circumstances, joy can co-exist with sorrow.
Colossians 3:1 Since you have been raised to new life with Christ, set your sights on the realities of heaven, where Christ sits in the place of honor at God’s right hand. 2 Think about the things of heaven, not the things of earth. 3 For you died to this life, and your real life is hidden with Christ in God. 
To learn more about trusting God’s love, listen here:
[1,3,4] Tyndale House Publishers. (2015). Holy Bible: New Living Translation Tyndale House Publishers.