But I have trusted in your steadfast love; my heart shall rejoice in your salvation. Psalm 13:5
When I read this Psalm I picture someone nearing the end of their life and looking back on the hard times and trials and being able to say "through it all, I trusted Jesus."
When David wrote Psalm 13 he felt like his enemies are winning. He cries out to God asking how long he will be in this hard place. He even says he feels like the Lord has abandoned him. Still his response and conclusion is that he continues to trust in the Lord. He has confidence in the salvation of the Lord. Whether it come on earth as physical salvation from his enemies, or ultimately as spiritual salvation for eternity.
David's faith can be an encouragement and inspiration to us as we go through life and seek the Lord. It's ok to feel lost sometimes. It's ok if you don't understand what the Lord is doing in your life circumstances. But through it all, you can keep trusting in and rejoicing in the Lord's salvation which doesn't leave you.