In Psalm 55 we see that David a type of Christ. Rather than return evil for evil to those who seek his life, David said he would pray to God for deliverance. Rather than pursue his own revenge he would petition the courts of heaven for justice. He was confident that the God of the universe would give to each person what he or she deserves. He will give peace to the guiltless and punishment to the guilty.
At the end of the Psalm, David encourages his readers to roll their burdens on the Lord rather then bearing them themselves. He trusted in the Lord’s ability to sustain His people because David had experienced God’s faithfulness in trouble many times himself in the past.