Psalms - Chapter 86
David's "Wish List"
A Psalm of David, this one is called tefilla, a prayer.
David asks G-d to hear his prayer, because he is poor and destitute. (The Radak says that although David had significant funds to his name, he was unable to access them while on the run from his enemies. This forced him to survive on help given him in secret by members of his Tribe and others.) David asks G-d to protect his soul because he is a pious person who places his trust in G-d. David asks for favor from G-d because he calls out to Him all day long. Finally, David asks G-d to gladden him because he dedicated his soul completely to G-d.
David says that G-d is all-good and the source of forgiveness. He grants kindness to people - even the wicked - when they cry out to Him. And so, David hopes that G-d will heed his prayer. He is confident that G-d will answer him, as he is crying out on his "day of trouble."
There's no other "god" - only He has any power. (The Radak says that the Heavenly spheres in their orbits only do what G-d told them to do.) All the nations that G-d made will eventually recognize and serve only Him. Only G-d can make the wonders of creation.
David asks G-d to instruct him so that he will know how to walk in His truth (Torah) and dedicate his heart to G-d's service. When this happens, he will praise G-d and thank Him for it wholeheartedly. G-d's kindness towards him has been great, David says, and He saved David's soul from the depths. (The word for grave - sheol - could also be read Shaul - King Saul, who sought to destroy David.)
Many enemies have persecuted David (Rashi specifies Doeg and Achitofel); they want to corrupt and destroy him. G-d, however, is merciful, compassionate, slow to anger, and full of kindness and truth. (This is a paraphrase of the traits of G-d found in Exodus 34:6.) David asks G-d to give him strength to endure his enemies' attacks; he is G-d's servant just as his mother was G-d's maidservant.
David ends the psalm with a request for a sign that his sin has been forgiven. When his enemies see this, they will be embarrassed of their attempts to harm him. When He does this, G-d will have comforted David.