A Psalm of David.
Do not fret because of evildoers,
Nor be envious of the workers of iniquity.
The word picture meaning of the name David is: "a person making secure the highest".
David wrote many of the psalms (to cut off the bitterness of chaos) and in so doing he was establishing his legacy as a person making secure the highest.
Of course David was far from perfect, nevertheless he always returned to his true north of seeking after God's highest purpose.
God called David a man after His own heart.
The psalms are a weapon to cut off the bitterness of chaos and you and I can pick up those weapons in the spirit of David and use them to make secure God's highest purpose in our lives and the lives of those around us.