There are a lot of favorite Psalms in the 120’s and 130’s. This is one of them. I try to read this Psalm every time that someone is going into the hospital for surgery. The reason why is as you read it, think about the knowledge that God has of your body. Think of the fact that God has known us ever since we were intricately woven in the depths of the earth. Think of how God knows how we have been knit together in the womb of our mother, and then take comfort in knowing that whatever happens in that room, God is ultimately the one who has complete charge and control of your body.
It is so important to remember that God has created our bodies so we ought to treat out bodies as a temple. Paul says this in I Corinthians 6:19. That means that even though God is in control of our bodies, we can’t think that we can do anything that we want with our bodies, while at the same time abusing them thinking that since we are faithful God will compensate for our faults. Take care of your bodies.
I stop reading that psalm at vs.19 because the psalmist seems to be having a hangover from psalm 137 as he wishes God to kill the wicked, aka his enemies. The Psalm begins and ends, if you count vs.18 as the ending, with the assurance that God knows not only our bodies but also the end of our days. God knows when our days will come to an end. It is simply a great psalm.